(C'm'on, now, I don't think it really needs an explanation.)
Anyways, I use iTunes for my iPod music of course. I also have Spotify, but I just started using the iHeartRadio app my boss introduced me to at work and I must say I'm liking it so far. The ability to share custom playlists and stations is pretty damn awesome. I spent hours putting together my own playlist that we listened to during our shift last night (I'm 3rd shift) because he happens to have a PA device that he always plays his stuff from on there. I don't know if I'll roll with a monthly subscription over the free Spotify, app, though, we'll see how it goes.
It's a mix of punk, alternative, and metal BTW.