Mycelium was the best android wallet for quite some time.
Unfortunately they have decided to support some shady russian ICO and to develop a bcash module instead of integrating segwit.
But it still works flawlessly for me (even tho some users report they have connection issues with mycelium). Has a nice UI too.
I think it's a great wallet but these days it's hard to recommend due to the lack of Segwit and that ICO crap isn't too impressive either. Their attempts to monetise it have been unappetising.
The only wallet really keeping up with all the developments is Samourai, though the UI is a bit blank for my tastes.