Christopher Nolan just doesn't make sense. First of all, I don't believe he would ever agree to it (just came off a blockbuster trilogy, would be working off someone else's script). Some people are saying that if he did it, it would be all gritty and such. I don't believe Nolan is dumb enough to Dark Knightify SW for a sequel. I think he would be able to make it like the others. But the thing is, I don't think he would want to.
I'm staying with Brad Bird (though Spielberg is definitely my number one).
By the way, if the new trilogy was a reboot, I would say my number one is Nolan.