Some of mine are grayjay, kotatsu, expenses, voyager, feeder, mull and syncthing
Most used: k9 mail, Firefox, Voyager. Favorite: termux is awesome but I don’t use it much.
Added: Trail Sense is another great app that I don’t use all that much at the moment.
Mull, 1List, Notally, and Cheogram are pretty heavily used.
Vanilla Music – the music player I use.