Cena won't win because it's rumored he'll be facing Sheamus for the title at RR. I'd say Batista, but he's supposed to be facing Taker and Rey at RR for the WHC (supposedly). Punk is a top choice, but he'll most likely be facing Christian for the ECW Title at RR. So that leaves us with 3 really good options.
1) Edge-Have Jericho as one of the guys holding his own in the ring and more or less cleaning house for a bit until a face Edge makes his return and just takes it to Jericho and dashes his dreams at being in the ME at WM.
2) HBK-This could easily set up the whole HBK/Taker II match at WM that HBK so badly wants. Whether or not we'll get this match or HBK/HHH at WM is still anybodys guess.
3) Kofi or Orton-Either way this ends up, we get more fire added to this fued. If Orton tosses Kofi, it could be used to make Kofi seem frustrated with the fact he can't take care of Orton thus causing a more sadistic side of Kofi. You could have him focus on taking out Legacy first before he goes after Orton. If Kofi tosses Orton out, not only does WWE have their "black superstar" they so badly want, but it assures Kofi a win and a title run at WM. As a result of his ruined chance to headline WM, Orton could turn on Legacy and blame this all on them thus resulting in a new storyline as well as a test to see how over Dibiase and Rhodes can be.
Although if we go with the whole "suprise" angle, let's for shits and giggles say Booker T wins.