I see nobody mentioning airsonic, the open source fork of subsonic. I tried navidrome but there you can't browse through folders or start a 'radio mode' (i.e. play related stuff in your library).
Another problem I found with navidrome are duplicate files in your library: since it is not folder but tag based, you'll end up with every track double, and there is no nice quick way to just play an album each track played once.
Is there a reason why people prefer navidrome over airsonic? Since I switched I feel so much more in control what I want to play.