I'm quite surprised that no one has mentioned Gil Scott-Heron, as he was clearly a very powerful, early influence on the genre. And if you think that rap is all about "thugs", or that rap artists aren't musicians, then you haven't listened to Scott-Heron.
For those who are interested, try "The Revolution Will Not Be Televised" and "In the Bottle".
For those who are interested, try "The Revolution Will Not Be Televised" and "In the Bottle".