When comparing AWS Cloud 9 vs WebStorm, the Slant community recommends WebStorm for most people. In the question“What are the best JavaScript IDEs or editors?” WebStorm is ranked 2nd while AWS Cloud 9 is ranked 13th. The most important reason people chose WebStorm is:
WebStorm integrates with Node.js to allow for running, debugging, and unit testing of Node.js apps.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Full terminal access
Cloud9 gives full terminal access to home directory. In their hosted Linux Ubuntu environment it has sudo powers. No UNIX commands have been blocked - npm, ifconfig, chmod, chown, tar, etc work. All commands can be accessed and any package can be installed.
And if the terminal is used when using Remote SSH feature it connects directly to the server and runs the commands on that server.
Pro Capable editor
Cloud9 uses their own editor called ACE. Besides the basics, it covers most important advanced code editor features such as code folding, converting cases, auto-completion, code analysis and refactoring, regex search and offers easy access to relevant documentation.
It also gives access to the CLI, has support for Vim and Emacs keybindings, includes multiple cursors and zen coding mode that removes all distractions and allows focusing on code.
Pro Great documentation
Cloud9 has extensive, well-organized documentation at docs.c9.io.
Pro Enables real-time online collaboration
An important feature of Cloud9 is the real-time collaboration ability. It allows pairing programs or perform code reviews really easily as well as simultaneously text chat.
Pro Integrates with AWS
Prior to being part of the AWS Toolchain, AWS integrates deeply with CodeStar and AWS Lambda, allowing you to build serverless architechtures.
Pro Offline editing
By installing and running a client application that syncs the local file system and cloud storage Cloud9 can be run locally. Great alternative for situations when the Internet connection is unreliable.
Pro Can be hosted on own server
Since Cloud9 is an open source project with source code available on GitHub, it can be run as a self-hosted solution on own hardware and behind a firewall.
Pro Git & Mercurial support
Git and hg commands can be run in the command-line, the same way as in a local terminal. There are also built-in add-on services for GitHub, BitBucket and GitLab.
Pro Runs any language
The runner has built-in functionality fo Apache, Node, Python, Ruby, Ruby on Rails, Go, CoffeeScript, Julia, Mocha and Shell script, but any other language can be used by creating a runner for it.
Pro Desktop application is available
Prior to the Cloud9 core source code being released, an Alpha version of a desktop version can be built from the source which is based from NW.js. Instructions can be found here.
Pro SSH Workspace
Allows you to connect directly to your external server via SSH. Modifying files directly on your server using a cloud based editor allows you to have the portability of the a cloud based workspace with the control of your own server (including complete DNS control).
Pro Debugging with breakpoints for NodeJS server side JavaScript
Breakpoints allow specifying a stopping points in the execution of the application. When these breakpoints are hit, the application will stop executing and give the ability to examine data such as local variables, run commands and control the execution flow of the application.
Pro Ability to clone multiple repos in one project
Cloud9 provides one free private workspace. However, I can host multiple projects there by cloning as many repositories into the root project directory, thanks to the full access terminal.
Pro Package manager
Similar to package managers for the desktop, Cloud9 also includes their own package manager, c9pm, which allows adding new software from a list of available utilities.
Apt-get can be used in the project's workspace terminal to install/update/upgrade software. Composer, Bower or any other utilities of choice can be installed to manage dependencies and packages.
Pro Provides with a simple way to deploy apps
Cloud9 allows quickly deploying apps via CLI. There are instructions on how to deploy to Azure, CloudFoundry, OpenShift, NodeJitsu, Modulus and Heroku. For example, all hosted environments have Heroku's toolbelt installed by default so all heroku commands are available from the get-go.
Pro Provides with own runtime environment
Cloud9 can connect to a dedicated VM to provide a powerful Ubuntu runtime environment in the cloud using Docker. Apps can be either run from the run panel where a selection of runners is provided or from a terminal.
Pro Support for most databases
In addition to launching a server to run code, Cloud9 will also host a database to develop against. Support for MySQL, PostgreSQL, MongoDB and SQLite.
Pro Browser testing support
Cloud9 integrates with Sauce Labs a browser testing suite that allows previewing the app in any desktop or mobile browser.
Pro Provides with a simple way to deploy apps
Cloud9 allows quickly deploying apps via CLI. There are instructions on how to deploy to Azure, CloudFoundry, OpenShift, NodeJitsu, Modulus and Heroku. For example, all hosted environments have Heroku's toolbelt installed by default so all heroku commands are available from the get-go.
Pro Node.js integration
WebStorm integrates with Node.js to allow for running, debugging, and unit testing of Node.js apps.
Pro Code refactoring support
To make sure your code can be easily maintained, you must first be sure to make it clean and tidy. This is the part where WebStorm really helps you. It automatically refactors your code by performing functions on it, such as extraction of variables, moving files, inline variable extraction, etc.
Pro Integrated code quality tools
WebStorm comes bundled with JSHint and JSLint. JSCS, ESLint, and Closure Linter can be installed via npm. They register as inspections and are customizable through IDE settings. They run automatically and will highlight potential issues. Pressing alt+enter on an issue will allow the user to view suggested fixes.
Pro Intelligent code completion
WebStorm has two types of autocompletion: structural completion and word expansion.
Structural autocompletion makes predictions based on its understanding of JavaScript objects, while the latter tries to predict the word currently being typed based on previously typed words. Word expansion also works in comments and docstrings and it's similar to vim's omnicompletion.
Both types of autocompletion work extremely well, have little to no problems and are quite fast even when loading suggestions on the go.
Pro Supports a wide range of plug-ins
Pro Maintains a local history
The local history feature in Webstorm tracks all your local changes in the source code that you are making. You can use it to view changes that you've made to your code and roll back whenever necessary.
Pro Typescript support
WebStorm offers typescript support for building typed JavaScript applications which improves refactoring and code completion, as well as helping to find bugs.
Pro Supports many JavaScript frameworks
WebStorm includes support for Meteor, Angular, and React.
Pro Reduces the amount of repetitive code that has to be written with code snippets
WebStorm includes a feature called Live Templates. Live Templates are predefined code snippets that can include variables. They're intended to increase productivity by reducing the amount of repetitive code that has to be written.

Pro Ability to base hot keys on previously used IDEs
When you install WebStorm, it allows you to choose from other IDE's for it to base it's hot keys on. So if you are switching from another IDE, it makes it a very easy transition and productivity is not adversely affected by having to learn new hot keys.
Pro Powerful git and GitHub integration
WebStorm has a powerful visual git tool, allowing for easy commits, visual diffing, merging, push/pull, rebasing, and inspecting the VCS history of a project. GitHub is supported natively - you can check out a project directly from GitHub.
Pro Built-in support for JavaScript task runners
WebStorm has support for Grunt and Gulp task runners.
Pro Built-in terminal/run tools
WebStorm (and really all of the IntelliJ IDEs) support the plugins throughout their plugin ecosystem which leaves you with 100s of tools to handle your automation tasks. There is a wide range of build-related plugins that help you by having pre-defined commands to execute with the click of a button. Out of any other IDE, WebStorm has by far the most coverage when it comes to tools for your development workflow.
Pro Theme support / tweaking
The theme is very easy to customize to your liking. You can change font-size, colors, highlighting colors, and more.
Pro Support for all major VCS systems
Webstorm supports not just Git and Mercurial, but Subversion, CVS, and Perforce as well.
Pro Multi-line select and editing
Pro Really good configurable code formatting
This integrates with other community tools like ESLint and editorconfig.

Pro Powerful Code Templates
Code Templates are powered by Apache VTL (Velocity Template Language) and allow for includes, custom variables, conditional blocks, iterators, and live templates.
Pro Special icons for most filetypes in project list
Webstorm comes with icons for many filetypes which makes it easier to find what you're looking for in the project list.
Pro Built-in web server
WebStorm has a built-in webserver that allows you to run projects from http://localhost:63342/ProjectName
.
Pro Has a built-in terminal
The IDE comes with a built-in terminal, a feature lacking in some lighter editors.
Pro Compilers for compile-to-JavaScript languages
WebStorm has built-in support for CoffeeScript and Dart.
Pro Support for Karma test runner
Karma allows you to execute unit tests and monitor code coverage. You can read more about using Karma with WebStorm here.
Pro CSS pre-processor support
WebStorm has built-in support for Sass which is one of the most stable and powerful CSS extension languages.

Pro Server and client-side debugger
WebStorm has a powerful debugger, with support for conditional breakpoints.
Pro Auto sync settings across team / machines / platforms
With the settings repository, you can easily enforce your development standards.
Pro Free for open-source development, students, and teacher
Non-commercial open source projects, and students and teachers (including classroom licenses) may qualify for a free license. There is a 50% off license for startups (under 3 years old). You can read more about it here.
Pro Different configurations for different projects
It is able to specify for example node versions, which will be used to run task for current project.
Pro Webpack support
Assists with configuration and understands module resolution.
Pro Cordova support
Cordova allows for building native mobile applications via HTML, CSS, and JavaScript.
Pro Dart language support
Autocompletion, syntax-highlighting, refactoring, and pub integration for Dart are supported in WebStorm.
Pro Coffeescript support
Autocompletion, syntax-highlighting.
Pro Low memory use
It may seem like a complex IDE and it does have a lot of functionality, yet it uses way less RAM than barebones-looking, Electron-based IDEs.
Pro Gulp support
Pro Interactive theme (color scheme) editor
Makes adjusting an existing or creating new themes a breeze. Especially due to things like inheritance, as well as easily exporting/distributing/importing the color settings which really only store where on deviates from the defaults (thus the resulting files are very small and relatively human-readable).
Pro Efficient and effective
Cons
Con Lacks subdomain options
Building an app that needs subdomains is impossible.
Con Part of Amazon Web Services
While the c9.io site is still up and running, Cloud9 is exclusive for AWS Customers only, and you pay the AWS Compute pricing when you use Cloud9.
Con Free plan asks for credit card details
Free plan requires you to provide a credit card due to the nature of Cloud 9's "Free Workspaces" to be relatively abused. According to the developers, this is the only way to prevent such.
Con Lacks a built-in Java builder and runner
While there is no built-in Java builder or runner currently, C9 has provided instructions on how to set them up. Instructions can be found here.
Con Does not accept New Registrants on c9.io Anymore
As being acquired by Amazon Web Services as part of AWS Cloud9, the c9.io service won't accept new sign ups.
Con Terminal will not work on Windows (Cloud9 SDK)
The terminal package does not work on the Cloud 9 SDK in Windows because it cannot find an appropriate unix shell. This might be a recurring bug undergoing fixes.

Con Occasional slow performance
WebStorm can sometimes choke all cores of the CPU. There are numerous reports of high CPU usage.
Con Not free for commercial use
A paid license is required to use WebStorm for commercial use. The license terms changed in November 2015 and currently require a subscription (per year: $59 personal, $129 for companies). Students can obtain a free non-commercial, educational license good for one year. There is also an option to pay on a monthly basis in addition to perks, such as a fallback commercial license that can be used for free.

Con Not open source
This application is proprietary, and thus cannot be modified, freely distributed, or trusted for security.
Con You may have to fiddle with the JVM memory settings in configuration files
To get it to run properly, you have to edit the JVM memory settings when you use Node.js. Node.js makes the small JS project you have into a "large" project that requires more memory.
Con Plug-in ecosystem isn't robust
Every framework or extension with any popularity whatsoever will have a plugin for VS Code. Sometimes they'll still support Atom. Only one in twenty will have native support for WebStorm.
If you want support for the latest libraries, you won't get it in WebStorm.
Con Non-native filesystem causes issues
The Java wrapper around the filesystem doesn't actively watch for file changes (by, for example, using the fsevents api on OS X), and as a result can become easily desynchronised from the actual filesystem.
If you have an external tool acting on your project (such as a gulp task or a third-party Git client), what you see in the file browser or in open tabs becomes out-of-date. There's a feature in the context-menu for manually synchronising directories with their real filesystem equivalent, but this shouldn't be necessary and is annoying to do. You usually remember to do that anyway after you've been trying to track down a bug on a line of JavaScript that Webstorm says doesn't exist for the last two hours.
It should be noted though that this is easily remedied by going to File/Settings/System Settings and checking the "Synchronize Files on frame or editor tab activation" option. It's also recommended to more explicitly represent your workflow within WebStorm itself. Most external tools/tasks can be handled with WebStorm. And if it's not in a plug-in, then you can handle it with the File Watchers.
Con Proprietary file dialogs
Webstorm doesn't use the native Windows and OSX file dialogs, which makes it more of a hassle to open projects.
For instance, you don't have access to your favorite folders on the left-hand side in their custom file dialogs.
Con Can't open multiple projects in a single instance
The only way to open multiple projects is to run a new instance of WebStorm which is not ideal. WebStorm can use up to 1-1.5 GB of memory.
Con Poor usability on option and menu navigation
You need to press a combination of keys or navigate through different menu levels to carry out the two most common things a developer does. For example, to run your code, the default is Shift+F10. To go to definition, you need to click on "Navigation" first. There is no sense to this: being forced to press a combination of keys hundreds of times or navigating through different menus can be a waste of time.
Con Bad default options compared to the competition
Examples are an unreasonably low number of undo steps and automatic saving (which causes webpack dev server to bundle VERY frequently).
Con Constantly trailing behind on support for its main features
The Jetbrains team do an admirable job attempting to keep up with support for the features they wrap, but they are running an un-winnable race. For example, WebStorm 11.0.2 hangs when trying to debug NodeJS 5.0+ projects (30+ seconds before hitting breakpoint). By the time they fix it, 5.1 will be out and something else will break.

Con Newer versions are increasingly unstable
This only happens when it's not a major version.
