This is way too difficult, seeing as I like all genres of metal... but doom is best.
Opeth
Iron Maiden
Atheist
Ensiferum
Ephel Duath
Mekong Delta
Pantera
Katatonia
Isis
Iced Earth
Blind Guardian
Candlemass
Mercyful Fate
Agalloch
Pain of Salvation
Arcturus
Spastic Ink
Death
Mithotyn
Megadeth
Korpiklaani
Carcass
Quo Vadis
Augury
Kalmah
Wintersun
Arch Enemy
Starchild
Vintersorg
Lykathea Aflame
At the Gates
Liquid Tension Experiment
Torture Squad
Savatage
Cephalectomy
Amorphis
The Lord Weird Slough Feg
Dark Tranquillity
Bloodbath
Into Eternity
etc... and stopping now before it gets any bigger.