I'm not all that experienced with those genres, although I've heard
Sunn O))) and liked them, but I really really like Empyrium... although their later stuff is folk.
Also, I strongly recommend this really short demo by a long-lost band called Eternal Darkness:
It has the same cover art For All Tid has, but it was released two years before For All Tid was.
I do album art for bands! Send me a Message or email [email protected] for more info. My website: http://curtisbotham.weebly.com/