When comparing GameSalad vs GDevApp, the Slant community recommends GameSalad for most people. In the question“What are the best 2D game engines?” GameSalad is ranked 64th while GDevApp is ranked 83rd.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Cross-Platform
Pro No-code editor
Pro Has a Windows(.exe) version on par with Mac
The Windows version is now upto date with all the features of its Mac sibling.
Pro Multiple publishing platforms
Can create and publish games for iOS, Macintosh desktop and laptop computers, Android, Kindle, Amazon FireTV and FireTV Stick, Windows 8 and Tizen devices.
Pro Gamepad support
Gamepad support is available as of 0.13.3.
Pro Free standalone viewer app allows instant, live mobile device testing
The GameSalad Viewer is a free app available for iOS, Android and Kindle. Once installed on your mobile devices, you can deploy and test your GameSalad games live on any mobile device running the Viewer that is on the same local network as your dev computer.
This even allows Windows users to test their games on iOS devices without a Mac device and without any complicated code signing or provisioning profiles.
And, you can even take your games with you -- once loaded onto your mobile device, a history option caches recent games on your device without any connection to the dev computer.
Pro Allows you to focus on the logic rather than code
Since the user mainly uses menu options there is very little code needed to be keyed in. This makes the code very easy to read and understand.
Hence there are many help videos on youtube
Pro Extensive community of seasoned professionals for support
Extensive community of seasoned professionals in all disciplines (graphics, game design, animation, physics, music, video production, marketing, etc.) producing tutorials, videos, publishing tips, free templates and who are willing to answer forum questions and help newcomers.
Pro Powerful expression editor and functions
Allows you to create expressions on par with LUA (it's back end-language).
Pro Custom collision shapes with JSON support
Allows you to import JSON data for custom collision shapes to use with Gamesalad's implementation of Box2d physics.
Pro Easy to publish
Software prepares your app so you can just send it to Apple. All my games are reviewed with no problems.

Pro Drag and drop editor
The drag and drop editor makes GameSalad very easy to use, no programming experience needed.
Pro Great engine
Very quick to learn and great for making games. Community is very open and helpful.
Pro Quickly add behaviors to objects
Prebuilt behaviors can be added to objects. This is a very efficient way to add a physics engine or make a platformer game.
Lots of behaviors are included, from the most advanced (Physics, platformer, top-down movement) to really simple ones (like the behavior to destroy objects when outside the screen or the one to drag objects with mouse or touch).
Pro Powerful events system to create games without programming
No need for coding using this system which is clear and powerful: events are composed of conditions and actions.
Actions are launched when conditions are fulfilled. This is a very beginner-friendly way of making games and is still efficient for advanced usage, contrary to most other "block"/"drag'n'drop" systems.
Pro Intuitive interface
Pro Based on GDevelop
The entire webapp is based on GDevelop, an open source native game development software available for Windows & Linux, so it benefits from its advanced development.

Pro Can download an archive of the game source
Even though the tool depends on having a server up and running, you can download a copy of your game to run locally, or host somewhere else.
Pro Great UI
Sleek and user-friendly UI.
Pro Can export your game as HTML5 and for Android
Games can be packaged for Android without relying on any third party tool. You can also export your game and download it to host it on your server or let it be hosted on GDevApp.com.
Pro Shallow learning curve
Cons
Con Bad editor
There is no scene zoom, search boxes, or snap to grid. There is also no ability to focus view on the actor or use folders for file structure.
Con Expensive compare with others
There is no free version any more and it is very expensive compared with other engines.
Con Poor editor performance
Especially when you're working on a big project.
Con No scripting language or SDK
If a needed behavior is not supplied by GameSalad, there's no way to add it.
Con Product is suffering - Lacking company leadership and no voice from corporate
Some customers are currently in a holding pattern from the lack of support and messaging from GS corporate. GS is currently unstable and developers are waiting for another update that has been going on from 2015.
No word or message from GS corporate about timeframes or deliverables.
You can read the ongoing discussion here.
Con Product is in Limbo - company is lacking developers
Con Doesn't support Windows platform (*.exe)
Doesn't support Windows platform (*.exe)

Con Depends on a hosting service
If the website goes down or closes down, you'll no longer be able to develop your games using this system (but you can download a backup of your game from time to time and open it with GDevelop).
Con Cannot deploy native games
For now, games developed with GDevApp can only be deployed for the Web. Android deployment is in the works, but even then, they won't be native since they are built with web technologies.
