For me, it comes down to three people, and all of them would be gunning for Dolph Ziggler and the World Heavyweight Championship.
Choice #1 - Ryback
Ryback gets one more shot at beating CM Punk for the WWE Championship in a TLC match during the first Raw of 2013, but that's only because CM Punk couldn't compete at the TLC PPV. Expect that upcoming match to be a watered-down version of what we would've seen had it happened last Sunday. But of course, CM Punk is going to face The Rock at the Royal Rumble, so Ryback's chances of becoming WWE Champion in two weeks are zero to none.
However, if WWE planned on keeping Ryback in a world title picture, they made shift his attention to Dolph Ziggler, who will likely cash in his MITB contract at the Royal Rumble and become World Heavyweight Champion. In all these scenarios, Ziggler will no doubt survive The Big Show at the Elimination Chamber. Ryback would win the Royal Rumble, go on to face Ziggler at WrestleMania...and probably win.
Choice #2 - John Cena
John Cena just finished facing Dolph Ziggler at TLC, with the MITB contract on the line. Cena lost due to AJ costing him the match. Since then, Cena has found himself dealing with AJ's bodyguard, Big E. Langston, every time he tries to get a little bit of revenge. It's highly possible that Cena vs. Ziggler, which has already been going on for over a month, will play out all the way to WrestleMania, where Cena will get a world title shot by winning the Royal Rumble.
The build-up to their Mania match post-Rumble will play out essentially the same as the Ryback scenario, and like Ryback, Cena will probably win the title at WrestleMania, and finally get some revenge. Oh, and he'd also become a world champion again without interrupting CM Punk and The Rock.
Choice #3 - The Miz
The Miz is the wildcard choice of the trio, but his chances of winning the Royal Rumble are just as possible as John Cena or Ryback. The Miz confronted Dolph Ziggler and AJ about what happened at TLC, and ended up getting attacked by Big E. Langston for mocking them. If you've read next week's spoilers for SmackDown, you'll know that Miz and Ziggler have a match, which ends with Ziggler getting a dirty win thanks to Langston. Miz, however, continues to taunt AJ after the match.
While this may or may not be the start of a world title feud at WrestleMania, if WWE wanted Ziggler to actually beat an opponent and retain the world title at Mania, then The Miz should be their go-to guy. Winning the Royal Rumble would enough of a victory for The Miz, whose movie comes out during the Road to WrestleMania.