My choice is Harry Lloyd, who played Son of Mine in the S3 eps, "Human Nature" and "Family of Blood."

He's an absolutely phenomenal actor (one of the best I've seen, to be honest), and his name was bandied about as a possible successor for David Tennant prior to the casting of Matt Smith. And while he wasn't exactly good-looking as Son of Mine (to put it mildly), he's actually gorgeous in real life:



He's a huge talent, and I think he'd be incredible as the Doctor.
Your picks?