Ranked in these QuestionsQuestion Ranking
Easy to learn, based on Entities and Components, the later being class-like objects that entities inherit.
Has open function binding systems, allowing easy creation of custom components.
Starling is just 12k lines of code and doesn't try to do everything - but what it does, as efficient as possible.
Pro Free and open source
Starling is available for free with code available on GitHub.
Pro Strong community support
Forum is always active with knowledgeable developers and with lot of inside info, and post mortems.
Con No IDE
If you like having some huge GUI akin to Gamemaker, Unreal, Unity, etc, Crafty is not for you.
Con Early in development