i don't know much about the best ones but i do know some underrated but really good ones. Find them at exp game app. Games like dragon heroes, demons hunter, conquer age
Why not download it and explore your own? It's better to learn from experience.
I haven't check. But I looked into Exp game and it says they are an application. Which I think, would't really allow you to play directly. Unless they have are a game application. And if I understand correctly, they are only giving vouchers for games.
I would highly recommend Clash of Clans and Starwars Commander for Android.
Clash of Clans