I think Vitali
This is based on consistency and longevity.
Bowe has the most impressive feat on his resume, clearly. But I am never someone who decides on these things with just what is on the win/loss column.
You look at Bowe's career and it is littered with inconsistency, he is one of the most talented ever, but his performances in the Golota fights were not good, Bowe was not in great shape, but Golota was hardly great. Things like this start bringing this comparison much closer in my eyes.
Vitali's performance in the Lewis fight also showed me that he could have competed with anyone. Yes he lost, and i believe he was deteriorating during the fight but it was one hell of a performance and you never know what could have happened, he had lots of success in that fight.
He was/is a great heavyweight in his own right, I think him and Bowe is a pick em, I think prime Bowe would have taken Wlad out, but Vitali I'm not so sure. I have always felt against the very best Vitali's substance over Wlad's superior style any day.
It is very close, and I would not argue with anyone either way. Bowe is clearly the more talented. I just feel Vitali was stronger mentally, and I think that matters when you are comparing great champions. He also has an iron chin which helps lol