I am not 100% sure, but my best bet would be Superman because he was hit with a ton of his weakness (kryptonite), and he could still not be defeated. Although, he did die, he came back to life, so my best bet would have to be for Superman.
Hands down SUPERMAN come people Thor has none on superman. Thor may be the god of thunder but superman has everything the whole pack. Super strong,Super fast and super smart.Even Odin the father of Thor can kick Thor blonde butt. And everything Superman has come out in cartoon and comic books he has never show all his strength because he fears that he will kill someone. So there.
Superman.... I think he is a bit stonger than Thor (even though Thor is a God) but faster, has heat vision and if he really needed to charge up he could fight Thor closer to the Sun and whoop his @ss
Superman. By definition he's more powerful. Nothing can kill him except a rock from a planet that was already destroyed anyway. This is why I find superman to be the most boring super hero...