The best thing about LibGDX is how complete and comprehensive it's API is. It covers OpenGL, OpenGL ES, Bullet Physics, Box2D and Freetype with a coherent API that's completely platform independent. It's platform support is also very good, being compatible with Apple iOS, Android, The Linux/Windows/Mac combo and even HTML 5. It also makes use of the best features of the Java programming language, allowing for very concise programs on the developer user side (all the typical Java verbosity is hidden behind LibGDX's API). The other best thing about LibGDX are it's own libraries for Entity-Component development, common AI patterns, particle systems, value interpolation and game pad support. It is also very easy to set up for Eclipse, NetBeans or IntelliJ development using it's absurdly simple setup tool. And if you don't like Java, LibGDX is also 100% compatible with other JVM languages like Scala. And last but not least: it's free software both as in free speech and free beer!