If you want somthing heavy get some cannibal corpse....
if you dont want such heavy singing get some
STRAPPING YOUNG LAD
they are one of my favorite bands out there at the moment...some of my favorite (and heaviest) songs are
"oh my fucking god" !!!!!!AMAZING SONG!!!!!!!
"home nucleonics"
"relentless"

Devin townsend (lyricist for syl is a genious....absolutly amazing singer and song writer)

if you want some stupidly insanly heavy music check out anal cunt or agorophobic nosebleed

if you like stuff like cradle of filth and dimmu borgir but want somthing less main stream and heavier check out stuff like "emperor" its not as gothic in the way that CoF and DB use poetry....but its dark and heavy

here are some other bands lol.....
Anaal Nathrakh
Anorexia nervosa
Behemoth

shhiiit im not going to make a huge list....if you want more suggestions then just ask.....

but if you actually like heavy music check out strapping young lads "city" album........i PROMISE you , you wont regret it.....its FUCKING AWSOME....words cannot describe it....lol...i live for that shit,.