I think Cena would definitely lose to Undertaker. The thing about Cena vs. Undertaker, though, is that it'd be a big draw (as a clash of two huge names who've never really feuded) and it'd be a great match. There's times that I really hate watching Cena (mostly his promos), but I'm not doubting his ability when it comes to matches. I really believe Cena vs. Undertaker has the potential to be as good as one of the HBK matches.
I like Rock vs. Brock II for this Mania too. Both have limited shows to appear on, so it makes sense with their schedules for them to feud. It can be like HHH vs. Brock is right now, ie each of them appearing every couple of weeks and sharing show time. Plus, Rocky needs revenge for Summerslam 2002.
:rock: