IDEA places an emphasis in safe refactoring, offering a [variety of features](https://www.jetbrains.com/idea/features/refactoring.html) to make this possible for a variety of languages. These features include safe delete, type migration and replacing method code duplicates.
Ranked in these QuestionsQuestion Ranking
Pro Good UNIX citizen
It follows the UNIX philosophy by doing one thing well (text editing) and interfaces nicely with other CLI tools.
Pro Will be familiar to vim users
Kakoune first started as a rewrite from scratch of vim, but then ended up being another text editor altogether. So it's inspired in a lot of ways from vim.
Pro Very expressive
Kakoune provides a very expressive set of commands, including various objects selection (paragraph, blocks, words), alignment support, conditional selection filtering...
This set of command is expressive enough to implement all the provided auto indentation logic.
Pro More modern than vim
Pro Text selection mechanism
Kakoune works on selections, which are oriented, inclusive range of characters, selections have an anchor and a cursor character. Most commands move both of them, except when extending selection where the anchor character stays fixed and the cursor one moves around.
Pro Actively developed and supported
Pro Smart refactorings
IDEA places an emphasis in safe refactoring, offering a variety of features to make this possible for a variety of languages.
These features include safe delete, type migration and replacing method code duplicates.
Pro Fast and smart contextual assistance
Uses a fast indexing technique to provide contextual hints (auto-completion, available object members, import suggestions).
On-the-fly code analysis to detect errors and propose refactorization.
Pro Lots of plugins
Many plugins are available for almost any task a developer may need to cover. Plugins are developed by Jetbrains themselves or by 3rd parties through the SDK available for writing them.
Pro Stable and robust
IntelliJ IDEA hardly ever crashes or has any issues that plague other Java IDEs like file corruption or slowness.
Pro Android support, JavaEE support, etc
A very complete development environment support.
Pro Support for many languages
IntelliJ supports many languages besides Java, some of these are: golang, Scala, Clojure, Groovy, Bash, etc.
Pro Intuitive and slick UI
IDEA has a clean, intuitive interface with some customization available (such as the Darcula theme).
Pro Clear and detailed documentation
The documentation is exhaustive, easy to navigate, and clearly worded.
Pro Free version available
There is a free community edition (open source) and an ultimate edition, which you can compare here.
The ultimate edition is available for free for one year for students but must be registered through an .edu e-mail account.
Pro Many convenient features
These simplify the daily work, e.g. copy/cut a whole line without the need to select it.
Pro Very powerful debugger
With ability to step into a certain part of a large method invocation (Shift+F7), drop frame, executing code snippets, showing method return values, etc.
Pro Gradle support
Pro Buit-in Git support
Con Small community
Con Default bindings do not play nice with OS X (Alt+???)
Con No real Windows support
Will compile under CygWin.
Con Written in C++
Con Slow startup
Startup can be slow deepending on system configuration
Con Uses a lot of RAM
Con Standard hotkeys behave differently
Seems like hotkeys assignment in Idea has no logical consistency.
Like «F3» is usually next match, «Ctrl+W» - close tab, etc — they map to some different action by default.
There is a good effort in making the IDE friendly for immigrants from other products: there are options to use hotkeys from Eclipse, and even emacs. But these mappings are very incomplete. And help pages do not take this remapping into account, rather mentioning the standard hotkeys.
So, people coming from other IDEs/editors are doomed to using mouse and context menus (which are rather big and complex).
Con Bugs are not solved as often as they should
They are more interested in adding new features or issuing new versions than solving bugs.
Con Cannot open multiple projects in the same window
Con Built with closed source components
The version with full features is not opensource. Parts of the code are under apache licence though.
Con Lack of plugins
IntelliJ supports a very small amount of plugins. Although these are 'quality approved', many features are missing and can't be implemented because of that.