When I used to use Windows, I always had the toss up between Winamp and Foobar. Foobar used less memory, but was ugly, winamp had better support, better features, but used around 5 meg more RAM.
When I moved to Linux around 5 years ago, Amarok was pretty average, not too pretty, yet nice support and decent backend [MySQL database ftw]. Amarok2 takes this 1 step more. I cannot fault it really on anything other than it crashes when my music share [over sshfs] goes down. This is somewhat understandable though. Quality is good on all bitrates [winamp sometimes seems to mess out with VBR at 320k]