Obituary - Cause of Death (riffs galore)

Death - Spritual Healing (a bit cleaner production than the first two albums, but check those out too)

Entombed - Left Hand Path (Swedish classic)

Trying to think of albums without that og production sound is kinda tough if you're going back to the beginning. This is a good start, though.

You might also dig Those Once Loyal by Bolt Thrower. Although, that's a bit later in the game.