#1 Shinsuke Nakamura
Needless to say, this is a long shot compared to everyone else on the list, but as we have come to learn as WWE fans, anything can happen on the road to WrestleMania. And you would be lying to yourself if you said John Cena vs. Shinsuke Nakamura wasn't a WrestleMania worthy match.
See who is stunned by Hulk Hogan's words HERE
With Samoa Joe recently arriving on Raw, it might be a while before we see Nakamura surface on the main roster, but it is only inevitable at this point. He just lost the NXT Championship in shocking fashion to Bobby Roode over Royal Rumble weekend, so there is a decent chance he could have some sort of role at WrestleMania.
In terms of how the bout would be built up, Cena could call out anyone on the roster (specifically someone from the “New Era”) to fight him at the Show of Shows and the King of Strong Style would accept the challenge. If you want to make a star out of Nakamura from Day 1, having him wrestle Cena in his debut match at 'Mania would undoubtedly accomplish that.