Norton, while extremely capable (one of the best actors of this generation) doesn't have the look of Dent. However, he wouldn't be the worst choice, because I feel if he were cast, he'd do an exceptional acting job that may allow us to forget the "look". Especially with how I imagine him portraying Two-Face.
Foxx? No, he's no Dent. I don't see him in the role in the least. I think his acting skills may be able to do it, but I just really don't envision him in the role at all.
Baily- I think could pull this off. Actually, I'm confident that he could pull of the role of Harvey Dent. Yet, one of the most important things is if I feel he could pull of the role of Two-Face, and the jury is still out on that. Out of the three, he definitely has the look to be the pretty boy D.A.
So, out of the three I feel that Edward Norton is the one who is most up to the task of playing the dual role. He is a big name and a very well respected actor. Baily, ascetically, is Harvey Dent but whether he could be the other half of the character worries me. Foxx, complete miscast.
-R