Hmm, I have to go with Rampage. His standup is far and away better than Tito's, his wrestling is good, he's strong as a bull, and he's incredibly hard to handle on the ground. Rampage is the champ for a reason, and he's better now than he ever was.
I will say that I too have read in old articles that Tito got the best of 'Page on the ground, but he'd first have to get him there. Also, Rampage isn't the same fighter he was so who knows if that is still true. I will say that Tito's ground game is far more effective than a submission game versus Rampage, in my opinion. You're going to have a heckuva time subbing Rampage, but anybody can get busted up. Heck, Arona would've beat Rampage had he not stopped pounding him and gone for that triangle.
But honestly, I think Rashad really showed a way to neutralize Tito's ground game, and I think Rampage is much stronger than Rashad, so I really see Rampage winning this by whoop ass.