When comparing Microsoft XNA Game Studio vs Rainbow, the Slant community recommends Rainbow for most people. In the question“What are the best 2D game engines?” Rainbow is ranked 79th while Microsoft XNA Game Studio is ranked 80th. The most important reason people chose Rainbow is:
Distributed under the MIT License.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Easy assets
it is very easy to import your own 2 dimensional assets

Pro Very easy to use
relies largely on drag and drop elements and has been used to create notable high quality 2d games such as DLC Quest
Pro Open source
Distributed under the MIT License.
Pro Written in modern C++, is scriptable in Lua
Pro Cross-platform
With support for Android, iOS, Linux, Mac OS X and Windows.
Pro Optional FMOD audio engine
Pro Supports Spine
Pro Physics
Box2D integrated with Lua bindings.
Cons

Con It's dead
It is not getting updated and Microsoft does not recommend using it anymore.

Con Limited platform support
Only supports Xbox 360, Windows and Windows Phone
Con Not as feature-rich as other engines
Con Small community
Being fairly new on the scene, there aren't much of a community to speak of.
