Re: Who should be the villain in the sequel for Man of Steel?
I think it's hard to say until we see this film.
I mean, if MOS is exploring A LOT of the sci-fi aspects like some rumours are leading us to believe (alien ships), then Brainiac is a logic second villain IMO (and I'd hope that Lex would be in the mix too, because he should be in all Superman stories).
But if their going for a more Nolanesque type story I'd expect something more along the lines of Intergang/Lex trying to create technology that could fight against Superman (and other aliens, since their experience with Zod and Faora). I.e. Metallo/Parasite.
Superman: Don't be afraid.
Lois: I'm not. Helicopters, danger, go, go, go! Then we'll talk.