If you prefer an open source app, native, complete, with a decent UI and an active developer community, the official one is definitely the best. And I mean Jerboa, because it is the official client made by the very same people that are making Lemmy (so always compatible and up-to-date with the server development).

Otherwise, if you don’t mind using a closed source app, Summit is the most feature rich one and it is maintained by a professional industry-level native Android developer who really knows what he’s doing.

Finally, if you want to experiment with a cross platform app, open source and well maintained, with a really nice user interface, have a try with Thunder.