Brainiac is great for a choice of villain because not only is he an alien invasion story, but he's also an A.I. gone rogue story, all of which is perfect for a science fiction action movie.
You can also use Brainiac's tech as an explanation for other villains, like Metallo, in the sequels.
Brainiac that Lex thinks is working for him but its the other way round .... but then Lex outwits him and gets him back.
Yeah, like in Morisson's New 52 run, Metallo and Steel easily fit into a Brainiac story.
Brainiac could also be interesting if they tie it into our general reliance/addiction to the internet, the scary power of tech giants in government, tech companies spying on everyone, etc. I believe in Morisson's run, Brainiac is the internet.
I also like the idea of exploring the theme of ambition with Brainiac and Lex, that drive people have to be better, to be the alpha, to continue expanding one's limits, something that perhaps Clark could learn from a little?
Totally. I love the idea of Lex and Supes working together to defeat Brainiac, only for Lex in the end to pull one over on Supes, take Brainiac's ship and flee to space to continue Brainiac's work (or perhaps to return the stolen worlds for the credit, live-streaming his space-faring escapades, earning back the attention and respect of the human race).
Brainiac would be the obvious choice but ultimately (for me atleast) it should be the story that dictates who the villain is and not the other way around.
I still believe that a straight up Action 775 adaptation is the way to go, Superman fighting for his relevance and for a future where extreme violance isn't always the answer. As such Manchester Black would be the obvious choice and in stead of having nobodies like Hat, Coldcast etc....you can sub in some Superman villains like Metallo, Liverwire maybe Silver Banshee as part of M.Black's Elite team. And while you're at it you can substitute Atomic Skull (appeared in the animated adaptation) for Parasite.
This is how I'd like to see lex portrayed.
Show him being even more intelligent than his teachers in elementary school, correcting them and even writing out complicated formulas they don't understand. His arrogance would already be showing.
Show him graduating HS at 12.
Getting multiple PHDs by 16.
Making his first billion by 19.
He develops a Germ phobia at an early age, so he is constantly shaving all his body hair, including his facial and scalp hair, and he wears gloves.
He Forms Lex-corp by 23.
He Becomes the wealthiest person on the planet by 24.
He buys up properties in Europe and Africa to get the mineral rights, and he has those who refuse to leave their town or villages, "disappeared".
He would have rock star status while out in public. He wears movie stars, models, and singers on his arms like most do jewelry.
The Ladies and men both love him, but he has no time, nor desire to have any close relationships.
He hires mercy as his personal assistant and bodyguard.
She shadows him everywhere he goes and keeps away the admirers that stray to close.
Lex would be on all the major magazine covers and make all the talk show rounds.
He soon grows bored with it all as he secretly hates people, but they are a means to an end so he continues the act, putting on a likable facade while doing so.
He would have Tony Stark level of intelligence, but without the quirkiness or humor.
Superman then shows up and everything changes for Lex.