Mine is Strawberry since it has a ton of options and plays a ton of formats. It's also (distant) fork of Amarok 1.4 and integrates well with KDE Plasma. I'm curious what other people are using these days. What's your favorite player?
If you liked Clementine, check out Strawberry. Clementine hasn't been updated since 2016. Strawberry is a fork of the Clementine code base and essentially picks up where Clementine left off.