I'm going to be light on the details here, but these are some baddies I'd really enjoy seeing during the current run on Justice League. Feel free to share any thoughts if you agree/disagree.
5) Injustice League - I love super villain teams! I'm pretty confident it's just a matter of time before a story with the Injustice League shows up again. I'm not too particular about the roster used. Obviously it should probably be made up of appropriate villains who counter each individual league member. I will say that I'd really like to see Bane be a member though.
4) Starro - We've read a lot of Starro stories over the years, but I'd like to see them re-imagine this villain for the new 52. Give us something besides the giant floating star fish.
3) Vandal Savage - Made a bigger impact in the animated series than in the comic books. And frankly we haven't really see him do a whole lot so far in the new 52. I just feel like his character is really interesting. Furthermore, he has all the required pieces to go toe-to-toe against the World's Greatest Superheroes.
2) Darkseid - Let's face it. The way things went down in Justice League issue 6 didn't really do this character...justice. Despite my terrible pun, Darkseid needs to bounce back in a big way.
1) Prometheus - Made famous by Morrison's run on JLA. I would very much like to see Prometheus make an appearance in the new 52. New villains can be like new superheroes in that they're difficult to establish and legitimize. Prometheus built quite the reputation for badassery in an amazingly short space of time. Bring him back and make him a consistent part of this book. No need to reinvent the wheel here. There hasn't been enough Prometheus stories.