Wladimir surpassed Vitali a little while ago in greatness. Vitali was great but not ATG at heavyweight, in my opinion, and clearly so.
Vitali head to head is a beast but fought rubbish competition and lost his biggest fights. Later in his career his lean back and tap - simlear to what Tyson fury is doing now became really frustrating to watch but it got him wins. I'm glad he retired....
Mainly because of the Lewis fight I'd guess. He was up but was stopped due to cuts. A legitimate win for but it was one of those fights where the loser gets a lot of credit for a good showing. He did have a very good chin as well which - at HW - is always well venerated.
Vitali is a natural fighter, be it boxing, kickboxing or w/e... Wlad is a manufactured fighter, hes even admitted this himself when asked about him and his brother.... Without doubt Vitali ability wise is streets ahead of Wlad and thats without taking the chin into consideration