In light of the news that a new Superman movie is in the works, and is being directed by Zack Snyder(who did Watchmen, 300, and Dawn Of The Dead), here's what I would do as far as villains:
-Darkseid: the most evil Superman villain, and also, the only one who can go toe-to-toe with him strength-wise. CGI would be a must, but it would look awesome.
- Metallo: Due to having a Kryptonite heart, he's another big threat to Superman, and would also make some great CGI.
- Toyman: more likely the creepy doll version from the cartoon than the Ben Franklin - looking one from the comics, but would work either way.
Other villains that could be used: Parasite, Livewire, Kalibak, Braniac, Mr. Mxyzptlk, and The Collector.