+1 for strawberry, coming from Windows and foobar2000, this is the only music player on Linux really up to the task of playing huge music libraries and doing it well.
Checkout Quod Libet. Better than foobar, which I used through wine for ages. It's just about the only GTK app on my KDE boxen and I gladly make the exception.
Well I've been using Linux exclusively for almost 20 years, and the only music player I'm happy with is MusicBee, which is exclusively Windows only. It used to be a nightmare getting it to run on Linux/wine, and it had a number of annoying bugs, but it's pretty solid now if you've got the very latest wine and a slightly older MusicBee.