underground hip hop artists

so i used to be really obsessed with like the really big 90s hip hop artists (2Pac, Eminem, Dre, etc.), anyway, i still am. but, i recently started listening to Tonedeff (and i loved, i mean loved Archetype). but that got me thinking what are some good underground hip hop albums to listen to. (don't just give me madvillainy, etc. i want your favorite underground album, not what most people think is the one people should start with).