To be honest, Wach wasn't KO'd or even knocked down against Povetkin and he took Povetkin's best shots like a punching bag for 12 rounds until the referee stopped it on cuts in 12th round. But Wach's chin is 10 of 10
As for this thread. Chuvalo was small compared to AJ, and he was easy to hit. I pick AJ by stoppage, Chuvalo gets stopped on his feet.