Rafa, and it's not even close. IF Rafa gets to the final (that's the biggest IF you could possibly imagine), he will be extremely tough to beat. Of course, Novak will still start as the firm favorite, but it's not going to be easy for him.
I understand the optimism around Fed as he has been playing some great tennis over the last few months. But I don't think he can beat Novak on plexicushion. If this was Dubai/Wimbledon/Halle/Shanghai, then possibly yes, I would have given him a good chance. But beating Novak on plexicushion will take a super human physical effort, and I don't think Fed will be able to muster one at this point, especially towards the end of a physically brutal tournament. One of Milos/Kei/Stan need to take out Novak for Fed to have a decent chance in the final, and I don't think they will.