Has nobody mentioned Elisa? I have to admit I haven't gone back 2 1/2 years to read all these posts, but I haven't seen it mentioned in recent times. I'm currently listening to Pirates of Penzance by D'Orly Carte, and it sounds great.
When I launched it on my media computer, it took only a few minutes to import 5,000 or so tracks from my NAS. It has a great UI, and is intuitive to use. And it's a default application for Solus (on Plasma, anyway).
For playing a single track or album, VLC is pretty hard to beat, too.