I feel like people would draw too many parallels to Luthor with a Brainiac storyline, unless Brainiac wasn't the real physical threat. Darkseid would probably be best, IMO.
And these people have lost it. Singer's movie wasn't bad - it fit quite well with the old Reeve movies, which was exactly what he was going for. It just wasn't what people wanted. He realizes that, and although there's no feasible way for him to really get rid of the kid, Singer was ready to make a real movie for the audience. Routh could buff up a bit, they'd go "wrath of Khan" on it, as Singer put it, and then they'd be set. Instead Warner tries to turn this into The Dark Knight with blue tights, a red cape and the biggest boy scout in comics? The Batman movies worked so well because of Nolan, and his vision and execution of that vision. Superman should not be handled the way Batman was, because he's a completely different character. They're polar opposites, in fact, linked by a single ideal. It's absurd, and I'm disappointed. The people at the top are clearly idiots.