The Android programmers in my office chose LibGDX and AndEngine over Cocos2D-X because of the lack of documentation.
I use Cocos2D-iPhone however and do find it's useful, but I also have a lot of documentation for the iPhone version
With regard to comments, other, cross platform options are
Unity is a 3D games engine.
Corona is a 2D games engine that uses Lua.
The Particle SDK is a slightly more general cross-platform solution with a background in games.
Today we announced that Particle Code has been acquired by Appcelerator, makers of the Titanium cross-platform framework.
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As of January 1, 2012, [Particle Code] will no longer officially support the [Particle SDK] platform.
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- The Airplay SDK is a C++ framework that lets you develop in either Visual Studio or Xcode.
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