There are some really nice music players out there but most of them work in this kind of tree way where they show you a small image of the album, and below all of the songs, or worst, directly show you all of the songs. I generally browse by looking at album covers and there I decide what to listen, so being able to look at the covers is something I really need. So far I’ve been using Elisa, which is the one who works the best for me, but then it got bugged so I switched to Lollypop, but I don’t like the GUI as much since it is a bit messy.
Basically, something more like this:
Instead of something like this:
I’ve tried Resonance and I really like it, but it seems really alpha and with not much active development for being a relatively new project.
You could use foobar2000 with “Album Art Grid View”
Edit: Ah, freeware (BSD license) but not open source.