For metalcore I agree with what everyone else is saying. Some underrated (at least in my opinion) ones are Bleed From Within, Crystal Lake, and Upon A Burning Body who actually did a cover of a WTF song. Remenissions I want to say is the song.
I'd like to add Ready, Set, Fall. The vocalist of this band is probably among the best metal singers that can both scream and sing really well just like Jesse Leach and Björn "Speed" Strid.
Funny story: Back in 2011 when youtube had an inbox I got this song as spam but the reason I decided to check it out was because it was called Buried Alive and I thought it was an A7X cover. Little did I know that there are a million songs called like that. Anyway I checked it out and I really liked it.
They only have one album because they broke up but the songs are really good.