Death Metal -
Necrovore - Divus De Mortuus
Deicide - Deicide, Legion
Morbid Angel - Altars of Madness
Cryptopsy - None So Vile
Incantation - Onward to Golgotha
Black Metal -
Mutiilation - Remains of a Ruined, Dead, Cursed Soul
Darkthrone - A Blaze in the Northern Sky
Burzum - Burzum, Det Som Engang Var
Bathory - Under the Sign of the Black Mark
Thrash/Speed Metal(whatever) -
Dark Angel - Darkness Descends
Metallica - Ride the Lighting
Exodus - Bonded by Blood
Venom - At War With Satan
Slayer - Show No Mercy, Hell Awaits, Reign in Blood
When trying to come up with lists like this, several factors influence my selections. First would be the feeling the music creates with respect to my preceived idea of what each genre represents - what the genre "should" sound like. I think the Mutiilation album is the blackest recording I have ever heard.
Second would be the bands importance in relation to the development of the genre. Necrovore had DM nailed down before almost anyone else, and no one ever mentions them. Glad to see someone did. That tends to conflict with the first factor however. I had to keep myself from typing Possessed several times. Dispite being "the first" DM band, they don't fully represent what Death Metal became, so probably don't belong on the list. I run into the same problem with Sarcofago, Holocausto and several other Brazilian bands.
The third would be the bands that first helped me understand the philosophy of each genre. For years I held None so Vile to be the end all of metal, these days I would probably agree with SRP in listing early Deicide and Morbid Angel as the definative DM bands.
Moonblood, Obituary, Monstrosity, Therion, Autopsy and some newer bands could be on there too, but then it might become a "favorite album" list, which is exactly what this thread is not supposed to become.
I would put some German thrash up there, but I would be lying.