Other than Wladimir, Fury would have the best chance, saying that he would have only a 20-30% chance anyway
You mean prime Vitali? The one who blasted Herbie Hide? Nobody would have a chance. Not even Wladdy. Current Vitali? Wlad, Povetkin...hard to say because we don't know about Vitali's health.
I'm not sure if you mean now or prime, but going for a real dark horse perhaps someone like (currently CW) Usyk with a bit more experience could be in with a shot of a UD.
Povetkin. Yes the Wlad fight sucked but Vitali has a totally different style and Povetkin is the toughest HW out there. Not saying I would bet on him, but he stands the best chance.
Wlad would systematically beat him down and stop him in the last 4 rounds. Tyson Fury would easily outbox him, either from the outside or the inside.