Best rapper ever? My vote is Kool Mo Dee!

[thrice]

What I look for in a rapper is his ability to address social issues and play with words. So much of the beginning of hip-hop was explaining the injustices and pain of the culture the from which the music is born. That is just lost in modern rap. It's all about sex, drugs, partying and materialism and does not provoke thought. It's actually pretty sad.

My favorites:

For pure lyric mastery (both the words and how he says them), I don't anyone much better than Talib Kweli. The first stanza of the following just blows my mind

Talib Kweli - For Women
http://www.youtube.com/watch?v=0qkjtK3O15Q

That song has an actual story to it and addresses social issues, both of which are missing from all genre of music, nowadays.

Also, Mos Def could lay down some amazing and thought provoking tracks. He and Talib Kweli were Blackstar, which was completely badass.

Blackstar - Respiration
http://www.youtube.com/watch?v=eeTnog5RRQo

The poetry of that song is just amazing: extended metaphor, personification, symbolism. I teach this song during my poetry unit.

Lastly, gotta give my love to Tupac. Some of his shit is so dope, I can't even explain it.