SR was a good way to bring Superman back to the movies and the public consciousness. Using Zod would be a misstep, though. I liked the notion of SR being heavily inspired by S:TM because it set the tone for the re-establishment of the franchise. But to re-use the bad guy from Superman II would be pushing it. In my opinion, the best alien villain would be Darkseid. Brainiac would be cool, too, but my feeling is that i've already seen brainiac on smallville, and while the characters would no doubt have their differences, I'd prefer to see someone completely new and never been seen on film before. And Darkseid could be really really cool...