Good question. Perhaps Corrie Sanders or Samuel Peter. I don't think Vitali was Ali, but if I put him in that fight I could see the same thing happening to George as what happened to him in the Ali fight, albeit later ( Round 11) What Vitali did have (other than being able to take the beating ALi did before he Koed George), was a 6 foot 7 frame and Stamina. He had a great chin as well. George would have to expand a great deal of energy. He was able to be hit, and would have to stay at a high level of output to keep up with an opponent he could not hit clean. I just think Vitali would out attrition George. You may say he has few great wins, but who BEAT Vitali? Without injuries Vitali would likely have won all his fights.
Probably Corrie sanders, who had him in fairly serious trouble early and came within the breadth of about a hair-and-a-half of doing to him what he did to Vlad, suggesting (though not demonstrating) that neither was a fluke. I think there's a pretty formidable case to be made that the crop of talent in the 1990's is superior to that of the early 2000's. One has to be careful with the modal logic of "the man who beat the man" type arguments, but if you dismiss this type of reasoning entirely we have no way of even deciding who's worthy of a title shot among active contemporaries.