I listen to mostly heavy music - punk, metal. Anything post-metal, post-hard core, prog and atmospheric stuff. As Starfer said, loads of heavier music also relax me. It can also be cathartic, or energizing. Really there is something for every feeling. I like bands that push the boundaries of genres. Not to mention there are amazingly talented musicians that I absolutely love. Especially when you go into post-metal or post-whatever genres where virtuosity of old school bands is taken over by a more focus on texture and composition.