It should NOT be, under any circumstances whatsoever The Rock. Not because I don't like him, but because it doesn't make sense for the LONG TERM. Once Rock is gone back to Hollywood, what then? Having Rock come in, win the title, appear one various talk shows with the title, hype up his movie career, etc does what exactly for WWE after WrestleMania? Nothing. So all that time spent on building up Punk's reign would have been for naught. I know the post was asking if not Rock then who, but I just feel that having him win the title doesn't help WWE at all on the long term and I don't know if they considered that when Rock announced he'd be in the main event at RR or if they're only starting to consider it now. And by the way, since when did guys start naming their own main events? Am I watching Hogan in TNA? I thought WWE would be better than that, and it shows the level in which interest and viewership has dropped to just do this.
Now, onto answering the question. I don't know anyone right now, currently on the roster who should take the belt off CM Punk. Punk is in a really tight spot because on one hand he has this awesome title run that may never happen again and on the other, he has this awesome title run that may never happen again BUT there's a very small amount of wrestlers who would be able to get that rub from taking the belt from him. When Ric Flair was NWA World Champion of course there was Dusty Rhodes. But to make Flair's title reigns in the 1980's really stand out, they had a succession of new people come through and try to be the one to beat The Nature Boy. And it worked. From Dick Slater all the way up to Sting, everyone tried to be the one to take the belt from him. Some succeeded, while others failed, and in the case of Magnum T.A., it was just a matter of an accident that kept him from it. But beyond all that, it made Flair's reigns interesting and legendary. It wasn't just Flair but the people after him who made it work. Dusty Rhodes knew this and didn't put himself over in spite of good business sense. Dusty was always the chaser, always the last line to get to Flair, but he never quite got to him (except for when he won in 1986). The point I am making is that for every Dusty Rhodes, there was always a Sting, Lex Luger, Nikita Koloff, Ron Garvin, Road Warriors, etc, etc. Always someone there but they never could. With CM Punk it's just Cena and The Rock, that's it. (Ryback is no longer a factor, thank God)
So stuck in this hard place he's in, Punk can only go one of two ways, up and beyond The Rock and successfully defend his title, once and for all, at least for storyline purposes, get that "respect" he's so desiring, if WWE does it in a classy way where they have The Rock NOT win the title. OR he can lose the title and everything he's built up and revert back to where? Mid-card? No. See, the differences between this and when Flair was champion was that even if Flair lost, you knew it was only a matter of time before he got it back AND that he lost in a way that didn't hurt him. Losing to The Rock will hurt Punk, badly. So until they have someone come in like a new Luger or Sting or Koloff or whomever, doesn't have to be based upon size, they should keep the title on Punk and build someone new (maybe someone from ROH) who will get that rub from being the one who dethroned CM Punk. The Rock doesn't need it and doesn't deserve it. Here's to hope WWE sees it that way too