...Sorry if this is a bump, but I couldn't resist.
Sure, Thor is a god, but did you see The Avengers? Even if it was a comedy bit, Hulk did manage to punch Thor into a wall, iirc.
If we were to put every superhero in the world up against each other on a level arena, I'd say Hulk would be the last man standing (the only exception being when everyone gangs up on Hulk to take him out) The only problem with the Hulk is that he can barely think straight while in his superhero state. I guess it's that flaw that keeps him level with the others, but I consider Hulk the physically strongest.