Pretty much everything they've released is essential with Eye For An Eye, Deliverance, and Wiseblood being the stand out-ish albums. Live Volume is one of the best live DVDs I can think of.

I love these guys, right up there with Acid Bath and Napalm Death in the 90's metal genre for me. I often just feel the itch for some 90's sludge, this band normally takes care of that. Great band.

Acid Bath are a fantastic band. I often go to CoC or Acid Bath when I'm in a sludge mood too.