I was the first to vote for brutal death metal! I haven't heard Nile or Cryptopsy, but I've heard Cannibal Corpse and I think that goes under that banner as well, and they S-U-C-K!!! Muddy riffs where it's impossible to find heads or tails, aggression for aggresions sake, bad songs, NO meldoy (and if there is it's terrible) and so on!
I haven't heard any noisecore as far as I know, but if it's like Anal Cunt without the funny songtitles, maybe I should have voted for that. "Flowershop guy" is great, because of the crazy chorus, but the other songs I've heard by them is 100% crap and noise!
I don't know if I've heard any grindcore either, but if it's Anal Cunt as well, then...
I wouldn't call Opeth & Arcturus progressive metal either. I would put stuff like Dream Theater in there. They're under technical, but I think that's more or less the same. Dream Theater might be more technical than other band in the progressive genre though. I haven't heard much progressive metal.