I've already expressed an opinion a couple of times around this interesting topic in some older posts and for the sake of conversation, here's a copy/paste from my Summerslam predictions/thoughts thread in regards to Brock Lesnar vs. Randy Orton which is actually very related to this discussion:
"... Either way, Orton is one of the top stars in the business so winning wouldn’t really make that much of a difference, nor would it hurt if him if he loses, so long as he is made to look strong, which I have no doubt they will do. On the other hand, I firmly believe that keeping Lesnar’s undefeated streak intact is all that more precious because this is a moment that should be saved for someone else that will need it more. Defeating Brock Lesnar would undoubtedly be a massive rub and boost for whomever accomplishes it and, at this point, I would even dare compare it to the Undertaker relinquishing his undefeated streak at Wrestlemania. Yes, I do feel it’s that big of a deal so on that note, again, I would save this moment for someone that will benefit the most out of it. Cesaro? Perhaps a Samoe Joe when he gets called up? You get my point…"
I think the paragraph above really sums it up. It is very important to understand - and I cannot stretch this enough - that pinning Brock Lesnar clean will be huge, for when the time comes and for whomever has the honors so, once more, you have to think about who will benefit from this. Orton didn't need this rub, Goldberg certainly doesn't need this rub and no old timer in general needs it. This is a moment that will establish a future star and I've personally pitched the idea of Cesaro going back at least three months.
They do call him the Swiss Supermam and we all are aware of his skills in the ring as well as the massive power he's displayed, having seen some tremendous spots from time to time. At the moment, with Cesaro pretty much doing nothing, in my view he'd be the perfect candidate.
Roman Reigns? Yeah, ok, I'm sure Vince will be jerking off to the idea and I obviously can't deny him being a solid candidate but I'm not really sure how the crowd would react to it.
Once again, I feel that at this point and time, Cesaro or Samoe Joe are the two best candidates, if indeed Wrestlemania in Orlando will be the place and time...