In a lot of death metal, especially the more brutal stuff, the details of the guitar work are lost behind muddy tones and walls of blastbeats. I want something where I can clearly make out the guitar riffs. And also where the guitar riffs are good, because there's a lot of death metal out there with just plain boring riffs. Beyond that I don't care where it falls stylistically. Some albums I would consider good examples: Death - The Sound of Perseverance, Cannibal Corpse - Kill, Behemoth - The Apostasy, Jungle Rot - Fueled By Hatred. Bonus points for particularly brutal stuff that doesn't use the suuuper gutteral vocals.