Heavy Metal

What's the best album of theirs? I don't know much about them and gave their newest one a listen and thought it was ok, not blown away though.

I'm in to stuff like wolves in the throne room and whatnot so am generally into this type of stuff, just thinking maybe i listened to the wrong album?

Mass IV is the one imo - I wouldn't have been able to enjoy Mass V as much if I hadn't picked up IV first.