Lupe Fiasco. His concepts and creativity is unbelievable. He has a song from the point of a hustler who comes back from the grave after being shot, a song about the ills of the world personified in a devilish character called "The Game," he has a song about how unhealthy fast food is, but he flips it so that he personifies a cheeseburger into a gangster. The list goes on and on...
Not only that, his lyrical abilities are probably the best in the game right now. Eminem might be the best in terms of technical rhyming (rhyming multiple syllables, etc.) but Lupe has far better metaphors, similes and punch lines.
Example: "The truth is limitless in its range... if you drop the T and look at it in reverse, it could hurt."
He's like a conscious Jay-Z, and a more flexible Nas (he can change up his flow and rap doubletime).
Last but not least, Lu never raps garbage. No tired clichés about hos, or how he sold crack, or how being rich is more important than being smart. He doesn't set a bad influence for the youth to imitate. He raps pure truth.