For me peak musicplayer UI is still my customized foobar2000 setup on Windows.

I need a waveform, a playhead, a good browser that can do both metadata based libraries and dumb folders fast and without lagging, a way to build/save/view/load playlists and a way to queue songs.

Most players are just too basic or make the wrong or to many assumptions about my collection. Or the interface is just too cute and dysfunctional for my actual daily use.

This means on Linux I currently use either mixxx or just VLC player, but I surely haven't tested every possible mediaplayer.