Oh man. I remember the days when I would listen to nothing but metal and more metal. Black Metal, Death Metal, Speed, Prog, Sludge, Grind and all those shit.
Got tired of it though and started to listen to house and trance instead, with the occasional ambient thrown in. I listen to Dragonforce once in a while as well just to feel mighty.
Didn't read the posts above me but I glanced the word Avant-Garde. Perhaps you guys might enjoy Sleepytime Gorilla Museum, <code>, Ved Buens Ende, In the woods..., Fleurety or Miasma & the Carousel of Headless Horses if they haven't been suggested.