I'd happily take Haye-Mitchell over Haye-VK. I think the problem with Haye - entertainment-wise - is that he blows pretty much everyone under 6'5" out of the water, but he isn't half as effective against giants. I'd pick him to beat the ageing VK and run Wlad a lot closer in a rematch, but the height and reach disparity in those match-ups puts me off.
I still think Solis is the best heavyweight talent, but he'll never ditch his Williams' diet. I love a good cake meself... I suspect Mitchell's on the limited side, though evidence of that doesn't really amount to much yet. He's exciting; that's the main thing.
I'd like to see Perez fight Solis for a shot at Povetkin, and the winner of that against Wlad.