I think I gotta agree that Cena would be the ultimate opponent for Undertaker. Think about it. Never in the last several years where the Streak was being built as something special at Wrestlemania, did we think Undertaker would actually lose. Granted, there were moments int the two matches with HBK where I thought that it may...just may be possible...but we all knew. If it was Cena vs Undertaker...we'd be watching a WM match where we would truly be witnessing the unknown. Think about it. Beating Undertaker at Mania is the one thing Cena has never done. It's the ultimate goal. And Cena rarely loses clean in any situation. It would be the one match where we wouldn't know what's going to happen.