Superman is the best hero, and everyone know about him for a reason: His relationship with his archenemy is unparalleled.
Think about it. A person who is nearly God like with super strength, super speed and powers and whatever is still a modest guy who cares for the people. In reality, he believes his "human disguise" of Clark Kent is his real self. In his core, the God-like being wants to just have a normal human life (Clark FREAKED out when he first discovered his powers and hated them). Superman is a disguise that he uses to SAVE mankind instead of wanting to enslave/abuse them as people with superpowers would naturally think of. I think that kind of modesty and simplicity is just something a lot of super heroes lack these days (Iron Man is a douche and Batman is a scary dude who wouldn't give a genuine fck about you other than your safety).
And his relationship with Lex Luthor is just amazing. Lex Luthor is a genius and he could improve the world if he applied his 12th level intellect along with Superman. But he doesn't because Superman stole his thunder.
From Luthor's point of view, he's trying to save the world from Superman, a super alien who has earned humanity's approval, while he (Luthor) a human is left in the dust.
Think about it. If you were really REALLY good in math (and you became so good because of hard work as Luthor was born in poverty), and suddenly some transfer student comes in and is undisputedly better than you in math, you'd obviously start hating him. It's human nature. And the tragic thing is that Superman KNOWS how Luthor feels. Watch All-Star Superman.