I agree with those who say they've got to bring a villain (or two) Superman could actually lose to. Superhero movies have been very, very reluctant to bring in the alien race/cosmic being characters, probably because it's hard to do it in a non-cheesy way. But the tech is good enough now, and those are the only opponents that can stand toe-to-toe with Superman. Doesn't have to be complicated - Doomsday is rampaging around, they fight, turns out DD was there to distract/kill Superman so Brainiac can drain Earth. Simple plot, nothing convoluted or cheesy. But he can't keep fighting giant rocks. Bring out the big guns.