Superman is one of my favorite superheroes. I don't actively buy his series, but I enjoy reading about him when he shows up in the various ensemble books I get, I'm a fan of his Timm/Dini animated incarnation, and I just really like the concept of an extraordinarily empowered individual who does good not because of a tragedy in his past but because it's just the right thing to do.
It annoys me when people say that none of Superman's villains are worthwhile because none of them can hurt him. That's ignoring four things:
1) Many of them (Bizarro, Parasite, Metallo, power-suit Lex) can hurt him physically;
2) Many of those who can't (Lex, Brainiac, Mxyzptlk) can potentially defeat him mentally without having to touch him;
3) Those who are a match for him neither physically nor mentally (Toyman, Prankster) can still be effective villains by menacing the people he cares about, including the citizens of Metropolis; and
4) Kryptonite is everywhere.
I'm just saying.