I see quite a few Go game apps for Android, including:

https://play.google.com/store/apps/details?id=uk.co.aifactory.go
https://play.google.com/store/apps/details?id=de.agrothe.go
https://play.google.com/store/apps/details?id=lrstudios.games.ego
https://play.google.com/store/apps/details?id=nl.tengen.gridmaster.go
https://play.google.com/store/apps/details?id=jp.co.unbalance.android.gocsdl
https://play.google.com/store/apps/details?id=mco.prj.app.bwgofree

Which of these, in your opinion, is best for:
1. Beginners (tutorial, hints, and so on)
2. Advanced players