Lex is a villain who is built up in movie two. Brainiac as the main villain of the movie who turns the humans against Superman.For as disninterested as I am in the general Superman mythos man I really want to see Brainiac on screen with this kind of budget. Especially if they go with the Animated Series supercomputer angle
Then movie three has Lex as the main villain with Doomsday involved.
Edit:
Just throwing stuff out there.