2. Brock Lesnar
Yes, the Beast is at #2 and it's easy to understand why. Throughout their time working in the WWE, the Undertaker has never beat Lesnar in a PPV (admittedly he did get screwed a couple of times) and so the idea of the Beast challenging the Dead Man for the Streak will have some interest. Furthermore there was that massive confrontation that everyone makes so much about (if you've heard about it, the actual footage is somewhat anticlimatic...) so the match will make headlines. Finally, if Paul Heyman is managing Lesnar at the time it would be good to see his second client go up against the Undertaker to succeed where Punk failed (plus who doesn't want to see Heyman tombstoned into the mat?). If the Undertaker could sustain one more battering that was more akin to his matches with Triple H than his less brutal match with CM Punk, there is no doubt this could be a great spectacle and there's a good chance WWE will agree.