BlueBoi

The Joker before people criticize my choice there is a difference between die and defeat as showcased in the injustice series joker would win but in that course die ultimately but he destroys what superman is all the way down to his core and creates an evil superman that would no longer even be considered to be a hero.

One Punch Man (OPM) one punch man already showed his colors against an alien from another planet who judging from the fight was at least as strong as Superman and won. no matter what you may believe one slap is not enough to take down one of the most powerful characters ever conceived. I mean he's so powerful he hates his own strength and is on the constant lookout for people stronger than him and that's his whole gag there is no one stronger than him he is the pinnacle of all races he is the strongest creature that exist and is often described as a god in human form. While I may hate Superman and think he is the greatest kind of trash a hero can be. my reasoning behind this is that he is so basic and impossible. not because of his power but because of his moral compass having been raised by humans and not being Jesus Christ himself, he is bound to become the worst villain imaginable because guess what there is no perfect being. that goes without saying not even Saitama fits that bill he doesn't really care about people he's in the hero business for fun and profit, nothing else. you may say that superman would win but you have to realize even pitted against the friction of leaving the atmosphere at speeds not even superman has traveled proves that he has a greater resistance to extreme situations than Superman has and Saitama's superpower of being able to transcend any limits to become all-powerful means that eventually he will become strong enough to destroy "Superman" in one punch.