As much as I love iTunes, after using Banshee, iTunes' playback sounds like complete shit. Banshee sounds way more crisp, *plays FLAC*, and has a better thump.
iTunes? Not so much. Unfortunately, the only Linux box I have now is Warpig -- which is an 800MHz PIII with 384MB of RAM -- and no Sound device D=. So I'm stuck with iTunes (and all of its sexy, iPod-compatible glory -- but at what cost!).