From Lois and Clark.
Mrs. Plat: I like your costume
Supes: Thank you, my mom made it for me.
Martha Kent: So now tell me more about this worman you're going to Luthor's ball with.
Clark: Lois is... we'll complicated. Comineering, uncompormising, pig headed... Brilliant.
Even though this isn't from Superman, or a one liner, I love this quote (got it from IMDB).
Lois: If you wanna kill Superman, I don't know why you're going to Smallville or 1966.
Tempus: She doesn't know yet. Oh, this is good. This is really good. Um, Lois, did you know that, in the future, you're revered at the same level as Superman? Why there are books about you, statues, an interactive game. You're even a breakfast cereal.
Lois: Really?
Tempus: Yes. But, as much as everybody loves you, there is one question that keeps coming up: "How dumb was she?" Here, I'll show you what I mean. Look (puts glasses on), I'm Clark Kent. (Takes glasses off) No, I'm Superman. (Puts glasses on) Mild-mannered reporter. (Takes glasses off) Superhero. Hello! Duh! Clark Kent is Superman. Ha, ha, ha. Well, that was worth the whole trip. To actually meet the most galactically stupid woman who ever lived.