I have to admit that what I listen to depends heavily on my mood and what I'm working on.
Edit: I change my mind... it's hard to qualify
Straightforward and Motivated: Drum and Bass.
Complicated and Motivated: Powerful Classical Music.
Un-Motivated: Background music but preferably Lyrical.
Sometimes though I just can't stand any noise and have to cut it all out to continue work. Unfortunately at work I'm in a big open plan trading floor next to trading desks and the problem with traders is they tend to get rather noisy!