Part of me says Cena is going to, because he is the full time guy and I'm sure WWE wants to build him up. And I'm not sure if this isn't a "passing the torch" moment, albeit an undeserving one.
On the other hand it is in Miami. That alone would actually make me pick Cena too, because WWE likes to make guys lose in their hometown. However, it is WM, and they tend to end on a feel good moment.
This is more difficult to pick than I thought it would be. And my opinion may change next week. All along I've felt Cena was going to win, but now I'm going to pick the Rock. I can't see Cena winning without there being a riot in Miami, much like with Punk in Chicago last year.
When it comes to this feud, they've done a good job with Cena. But that's mostly cause he's shooting, while the Rock is entertaining. I can't help but feel the Rock is handcuffed a bit in what he can say about Cena.