Pandora for me.
Pandora annoyed me because I can't pick my music really. Like, I tell them I like lacuna coil, so they play 15 bands that they THINK is like Lacuna Coil, when I really just wanted to hear Lacuna Coil. I.e. they won't play the band I name, just ones who are musically similar but NOT the same... which is annoying. That and they cut me off after like 2 hours or whatever.