I don't really want to be involved in this discussion, because I don't care so much about rap.
But:
Grandmaster Flash
without him there would have been no rapping at all.
Fun fact: my sister had the 12" of the Message, she was 15 when this was released, I was 10.
she's no rapper either, she was a disco blondie
Public Enemy
love those voices
Beastie Boys
ditto