Yeah, probably Tua after Frank finds a way to lose. Bruno's chin is underrated, but his survival skills weren't great. That said, his jab and stiff right hand ought to give Tua something to think about, until he gets caught by something big and stays hit. I think the Rahman fight as said above is a good comparison.
i go with everyone other than Balder. Tua late after being behind early. prime for prime Tua had lots of energy.