To me, I've only heard Killswitch, Shadows Fall and Lamb of God. I hated LoG before I got into extreme metal, but now I kinda like them. Chris Adler is a drummer that stands out from the generic metalcore drummers, imo, with his creative use of double bass fills and whatnot (at least for metalcore.)
Otherwise, I haven't really listened to any metalcore, only what I've read on message boards. I don't feel like weeding through the crap to get to the decent bands, who are essentially watered down more-mainstream thrash.
On another note, the constant praise of Sevenfold by the mainstream critics is fucking annoying. How they get praised for their "innovation" of guitar riffing. Hey critics and mainstream idiots, Maiden was doing that in '80. Opeth was doing that in '95. In Flames was doing that in '96. etc. And their drummer, who I've seen been called "the best drummer in metal today", isn't terribly special. Dave Lombardo was doing that stuff 20 years ago that Sevenfold's drummer does now.