During times that require high concentration (like programming), I listen to drum and bass. I find its repetitive nature combined with high energy resembles something like auditory caffeine without the crash afterwards.

Music with words or highly technical music (like jazz or prog) distracts me too much because of my musical background - I want to listen to every intonation, play the notes over in my head, try to figure out the scales, etc. But technical music is perfect during tasks that require only motor skills, like soldering or writing documents (rock, metal, sometimes jazz)