I enjoy the unholy trinity of black, death, and doom metal (and many of their subsequent sub-genres) and have been rooted in such for many years now.
My favorites und why:
diSEMBOWELMENT: Death/Doom Metal from Australia. Transcendence Into The Peripheral is a masterpiece, hands down. Their ability to perfectly mesh together slow, crushing doom, furious blasting death metal and surreal, peaceful ambient passages is well-executed in such a way that nothing seems out of place or forced, it all just flows together. Huge inspiration to me, unfortunately they broke up after their one and only full-length, but to this day they are considered the Godfathers of Death/Doom.
Deathspell Omega: Si Monumentum Requires Circumspice. Fas -Ite, Maledicti, In Ignum Aeternum. Paracletus. I need say no more. Best trilogy ever, in anything. Boundaries were not meant for them, and they prove this with their latest installment Paracletus.. very technical, experimental, dissonant yet perfectly executed chaos whose malevolence is sincere. Nothing is more "black metal" than they are at the moment. France's one redeeming quality.
Blut Aus Nord: France's other redeeming quality. Metaphysical Black/Extreme Metal as they so deem themselves. Memoria Vetusta II - Dialogue With The Stars is an unbelievable piece of work and a good accompaniment to psychedelic journies.
Inquisition: They prove that 2 people can create some heavy shit. Their riffing style is fucking awesome for lack of a better term, very ritualistic and dissonant black metal. Columbia wins.
Corrupted: Japanese Sludge/Doom Metal. With lyrics in Spanish. Released dozens of splits with grind bands with ultra-sludgey tunes, but their full-lengths usually consist of hour-long opuses that, in the vein of diSEMBOWELMENT, blend tranquility and monolithic doom. El Mundo Frio is majestic.
Then there's Drudkh, Gorguts, Mgla, Weakling, Lurker of Chalice, Grand Belial's Key, Satanic Warmaster, Immolation, Ea, Xasthur, Leviathan, Abyssmal Sorrow, Summoning, Burzum, Benighted in Sodom, Krohm, Judas Iscariot, Spawn of Possession, Ulcerate, Peste Noire, Arghoslent and hundreds of others. Those up there are just my top 5.