Honestly, for me its way too difficult to predict the winner now !.. a LOT can happen in the 3 months time..however, based on the current form of players, i can think only of nadal or djokovic( assuming, players get no injury).
...my inner mind says Nadal might walk away with the RG 2012..
pressure will be on djokovic b'coz :
1. he's the Hottest player on tour now.
2. He's won all 3 other GS - ( Aus open, Wimbledon & US OPEN)..he would want to complete career GS.
3. He's trying to be the first man since______ to win all 4 GS in a row( if not in order)
4. He's already disclosed to everyone that RG will be his #1 priority..so i am assuming he'll be super-fit by then..
5. can't think of any other..
.although if federer wins, it would make millions happy( including me)