Roy Nelson
Nah, back then Nelson would have gotten mauled. Even now I'm not sure he'd win. Nelson has declined as well but Carwin's ring rust might give Nelson the advantage.Nelson would have beat him then and will beat him now. Frankly, I'm not sure he can beat anyone right now...maybe Struve, maybe Brock, but no one else.
Bigfoot would be a great fight to shake off some ring rust. Wouldn't mind seeing him against Arlovski down the road.