Thor VS Superman debate
Superman has super strength, laser eyes, ice breath, x-ray vision, super speed, and many more. The only way Thor has a chance against him is if Thor trains non-stop on magic. Since Superman is definitely worthy enough, he could just steal Thor's hammer, making him a powerless, normal guy. Superman then will own Thor with no trouble.
The Man of Steel
While an interesting point is that Thor's hammer can be wielded by ANYONE worthy (Beta-Ray Bill) and Superman is consistently one of the most pure-hearted individuals on Earth and could potentially lift the hammer and strip Thor of all/most/enough of his power to make this a very one-sided fight. Besides Clark is a kind, fair, person trying to inspire others. Thor is arrogant beyond his training, and would rather not use his brain. He's not stupid but is hotheaded and lusts for battle.
Saying for some reason this is not possible, Superman could still win. Thor is strong but Superman is on a whole other level. Hercules is strong enough to fight Thor evenly/win. Superman is as strong as/stronger than Doomsday. While he did die the first time (after sacrificing several key moments to save people) the consensus holds that Superman is stronger or gained more from the experience. So another way to look at this is: Superman can beat Hercules (he even beat DC's Hercules and Atlas at once) but can Thor beat Doomsday? And Thor, while strong, doesn't have the brute strength or durability to muscle past Doomsday.
Superman Man of Steel
Superman is probably one of the most overpowered superheros of all time. Although Thor is a god who can strike lightning and fly. Superman takes machine gun bullets to the eye without flinching. Superman has all sorts of different powers that would be helpful for any fight. He would be the leader for and league. Good nature and full of justice. Most of all!!! Speaks proper English.