Generally speaking, I'm just looking for something that reaches out, grabs me by the lapels, and starts shaking me. Of course, that's pretty vague, so...
In general, I happen to like stuff that's got some appreciable texture to it; dense soundscapes are always appreciated, as is thickly-layered production. Songwriting, of course -- I don't care if the band can play six thousands RPMs and change meters every one-point-three seconds, if they can't write a good song. And urgency, too; many a great band has been done in, in my opinion, because their stuff just rambles on and on without any purpose, or direction, or vitality. Memorable melodies and thoughtful lyrics are also big pluses.
Well, that's what I look for, anyway. Genres don't matter too much to me -- I like what I like, and I don't care if that means my CD changer is loaded with everything from Aimee Mann to Killswitch Engage at the same time. And so far as originality goes... I like to hear bands that think outside of the box, but there are apparently so few of those who can do that and manage most of the above that I'm just as likely to give points to a highly derivative band with better songs.
There are my two cents; I'm not at all sure I phrased it well, but... what are you going to do?
--Brian
