I'm hoping for Nadal. The long layoff should hurt him...at least you'd think it would.
Even apart from that, Murray is not a guy Federer wants to face at the AO at this point. With the monkey off Murray's back, it's a mismatch on that surface.
Federer at least had a chance in the match against Nadal this year, but just couldn't sustain his first set level of play.
But I think there's a decent chance Nadal loses before the SF.