Antoine Cason is the best corner in the draft, IMO.
This is just one of the reviews I have read about him and there are many more just like this.
"Cason has the ability to be a true shutdown corner. Not only does he have the athleticism, quickness, and ball skills, but he has the attitude of a top tier corner. Cason will not back down from anyone, and loves be tested. He shows the ability to turn and run with receivers, and has the ability to locate the ball while it is in the air. Cason does not shy away from run stopping either. He is very active and quickly reads a run and aggressively pursues the ball carrier."