At first glance at the thread's title, I thought the OP was considering studying music, to which my initial advice would have been a simple word: Don't.
But my 'study music' is pretty much anything on my computer, as I generally can't be assed to skip tracks unless I'm kinda pissed off. So, a choice between classic 80s stuff, Gary Moore (also 80s, but worth noting), HIM, TF2 soundtrack or random 8-bit video game soundtracks from the Sega Mega Drive era.