Some random villain thoughts:
1. Lex Luther is a critical character, but ultimately should not be the villain of the first movie. The first movie needs to be *about* Superman, above anything else. You can have Lex Luther as a supporting character, but there needs to be zero ambiguity that Superman drives the plot of the movie. Lex as villain would compete too much with this. He can be the villain for movie 2, along with stuff like Metallo or Bizarro as his muscle.
2. Brainiac is a solid villain I'd love to see in the movies, but probably best saved for later, like the hopeful third movie in a trilogy arc. That said, when he's introduced, absolutely use the TAS Kryptonian AI angle. Brainiac should be a borderline "superhero crossover" villain, someone who exists in a place where Superman can only sort of compete on his own ( my vaguely preferred Superman 3 outline would basically be "Superman and Lex Luther team up to save the world from Brainiac ).
3. Zod is overused, but still has some potential to explore. I wouldn't use him soon, or at least not in one of my first three Superman movies, but if I did use him? I'd lean into a more "Khan Noonien Singh" angle, where he's *not* the unrepentant impossible megalomaniac. He's a ruthless ambitious warlord, but in his own way also loved Krypton and can be dealt with as a person. The denouement of such a story, natch, would not be Zod dead or cast back into the Phantom Zone, but Zod and his followers "trapped" on a suitably habitable red sun planet that is now his to develop. Does he really care about rebuilding Krypton or is it just about personal aggrandizement and conquest? Here is his chance to prove it one way or the other.
So, who *would* I use for Superman Movie 1? Honestly, its not *that* important, because the villain of the first movie shouldn't be important in their own right. The movie is Superman's movie, the villain is just there to be a cinematic manifestation of the challenges of being Superman. The only thing that must be so is that the villain *isn't* directly linked to or caused by Superman. If you use Mongul, then he's not coming to Earth looking for Superman, he's coming to Earth because its the next planet on his path of looting and pillaging. Etc.