For me, Clash of Clans and Clash Royale are two of the best games for Android.

I'm been playing these games for months. It never gets boring as there are so many strategies and things to discover and learn. I really like these two games. 

You can also check out the Clash Royale private servers I have on my blog which is absolutely fun. 

Here's the link: https://clashroid.com/clash-royale-private-servers/