It's far too early to pick one guy and say he's my choice to outlast everyone else. However it feels about the right time to list the men I currently think are favourites and a few longshot contenders.
Top of the list has to be John Cena. The reasons should be obvious. He is WWE's most heavily pushed and relied upon act and has been for years. He is the top drawing regular performer and so placing him in a prominent position on the biggest card of the year is a perfectly sensible business move. Cena versus any of the part time attractions mentioned in connection with 'Mania XXIX would be big business for WWE.
A Cena victory could set up a lucrative rematch with The Rock. Going against WrestleMania XXVIII's "once in a lifetime" marketing is not enough to stop that being a strong possibility. It could also lead Cena to a bout with current WWE champion CM Punk. We've seen that match far too often for it to be considered special any longer but the match would be a way of portraying 'The Second City Saint' as Cena's equal, especially if he were up beat him.
There's even the potential for Cena to win the Rumble and challenge for the World Heavyweight championship. There's plenty of time for Sheamus or Randy Orton, and maybe turn heel, to win the belt before 'Mania to give Cena a main event opponent.
Speaking of Sheamus and Orton both seem like possible Rumble winners. A WHC match between the two has been rumoured for WrestleMania XXIX. Sheamus could regain the big gold belt from Big Show and 'The Viper' could win the 30 man battle royal before turning heel. Orton v Sheamus would be a fresh programme and match that would allow WWE to continue presenting 'Great White' as a genuine headliner, something which remains inexplicably high on their priority list.
It could just as easily be 'The Apex Predator' dethroning 'The World's Largest Athlete' and Sheamus winning the Rumble. Although saying that it would mean Sheamus winning two years in a row, which doesn't seem terribly likely. The current writing system seems to be against repeat performances such as that.
Another guy who seems like he has a good chance is Ryback. He's received a substantial push all year and his profile has been raised considerably by his recent rivalry with CM Punk. While the WWE champion is probably going to be moved away from 'Big Hungry' over the next few weeks, to allow adequate time to hype his clash with 'The Brahma Bull', the chances of Ryback dominating the Rumble seem high. I'll be surprised if he's not in the final four.
Royal Rumble winner?
Should Ryback win I'd expect him to challenge for the World Heavyweight title. The WWE title scene will be dominated by established headliners throughout 'Mania Season. Besides, Ryback challenging for the WWE championship is well worn now. Should 'Big Hungry' win wrestling's most prestigious battle royal I could see him going against Big Show or a heel Orton. If it were the latter the match would naturally culminate with Show being muscled up for a Shellshock, proving to every man, woman and child watching that Ryback is the strongest in the land.
A Brock Lesnar win isn't beyond the realms of possibility. It could set up a battle between he and The Rock for the pay-per-view extravaganza, if 'The Great One' were to topple Punk of course. That would a fantastic match for WWE to promote: a Hollywood movie star against a former UFC champion for the promotion's top prize. It would be a great way to entice extra media coverage. It's one of the best matches WWE could go with.
Dolph Ziggler is another wrestler with a narrow chance at winning. While he's failed to capture a world title in 2012 (although there are still two weeks left) 'The Show Off' has worked his way up the card to a spot where it's not impossible to imagine him winning the Rumble. Pay-per-view outings against headline talent like Randy Orton, Chris Jericho, Sheamus (he sort of counts), Punk, and John Cena have helped his standing a great deal. It's possible WWE will speed up his slow elevation with a Rumble victory. If it happens I imagine Ziggler will be challenging for the WHC at Elimination Chamber or 'Mania.
What could harm Ziggler's chance is that he still has the Money in the Bank briefcase to use. An argument could be made that that already presents a clear route to the world title for 'The Heel', making a Rumble win unnecessary. Ziggler winning the Rumble and still having the briefcase could be made to work but it would involve WWE passing up a chance to elevate someone else. I don't think this is the former Spirit Squad member's year. Ryback seems more likely.
Finally there's the Undertaker. If he were to win the Rumble he would make a natural opponent for CM Punk. 'The Voice of the Voiceless' retaining all the way until WrestleMania would allow for a Streak versus long title emphasis to be placed on the match.
Alternatively The Rock could defeat Punk for the belt and challenge The Streak at 'Mania. Both Rock and Punk have the status to be credible and believable challengers to Undertaker's undefeated status. The longest reigning WWE champion of the modern era challenging The Streak would be a great main event for next year's extravaganza. That's the match I want to see.