It's clear we have a different opinion on hard durability. Thor can take punishment, but his skin is not as tough as many of the others on this list. Like I said he's also been hurt by a bullet, though it's more the exception than the rule. Even still, you likely wouldn't see that from many others on this list. Again I think classic Hulk and modern Hulk are perfect examples of differences in hard durability. We disagree on this, no big thing, but ditch the petulant attitude.
Not petulant, but an indignant attitude based on your projection of Thor been next to last when history proves convincingly otherwise. I do not based my opinion on what fans or writers that are bias might say, but on an educated guess based on hard facts. If Thor can walk through the core of a Sun, it means that he's beyond bulletproof; otherwise he would be dead miles before he gets close to the Suns' surface. And he supposed to be threatened by an ordinary bullet? Now, Marvel officially have stated that Thor is bulletproof, but I knew that a very long time ago based on facts- not opinion.
There is hard durability, which is what is asked for by the OP, and then there is damage soak. And then there is durability vs. physical attacks or durability vs. EP, heat, cold, radiation, etc.
No one is questioning Thor's damage soak, his ability to take one hell of a beating before dropping. It is his hard durability that is in question. Thor standing in the sun...awesome display of durability vs. heat and radiation. Not informative, though, about Thor's hard durability vs. physical attacks.