Not sure the easiest way to get a list of the top Android libraries on GitHub, but here's a sample of some that are Apache 2.0: https://github.com/ReactiveX/RxJava http://square.github.io/retrofit/ http://jakewharton.github.io/butterknife/

FWIW, my Android app's codebase has 18 Apache 2.0 dependencies, 1 MIT and 2 BSD. Maybe since the large libraries mostly use Apache 2.0, the smaller Android devs just follow suit?