Wolverine's healing factor is commonly misunderstood. His healing factor doesn't stem from the brain, as if his brain is detroyed completely, a new brain will form. His healing factor is up on Deadpool's level, as if he decapitated, he will survive it. In the Xavier Protocols, his head must be far away from his body. read more
Hulk's healing factor does come from his brain. If he was to be decapitated, he will die instantly. Hulk's healing factor does increase when he gets angry, and when at World Breaker Hulk, his healing factor is better than Wolverine's at that point. read more
The thing is, Wolverine's probably got the best healing factor but he is constantly healing his own body from the adamantium bones so that slows him down. And Hulk doesn't exactly have a healing factor so much as a pissed off factor, the angrier he gets the stronger he gets (including healing abilities). read more
You CAN'T drown Logan, and cutting off his head isn't enough, in Earth-807128 (Old Man Logan), Deadpool wasn't shown, maybe he was dead, and Wolverine's healing factor was really slown down, but he survived being eaten alive by Hulk. read more
The Hulk has the most powerful healing factor in the M.U. It's laughable how much more effective it is than Wolverine's. Deadpool would be a better comparison TBH. Also, don't just downvote because this answer is a bit cocky. It's true. read more