I think Joshua will win, he's too strong and too young for the current faded, inactive version of Klitschko.

Wlad, despite being past his prime, would still likely beat anybody else, but not Joshua.

However, I'll be rooting for Klitschko because he is underrated as an all-time great heavyweight, and because although he's age 41, he's taking on the best prime heavyweight in the world.