To be honest I prefer Lex in Smallville he was very sympathetic and understandable in Smallville. I feel like they shouldn't have introduced him as a straight up villain in the movies I feel like they should have written him in a way that leaves people thinking and or wondering if he's right. I've always thought a good way to reboot him would be for him to start out as a genuinely good man but for him to have "one bad day" happen well for Lex it would probably be a series of bad days.

This is how I'd do an origin for Lex he'd be the bastard son of Lionel Luthor raised by his single mother who may or may not have health problems and he'd spend the majority of his life hating and envying his father. Eventually his mother dies and due to not being able to afford proper health care and he decides to devote himself to his studies and building an empire of his own so he could fix the world eventually taking his father's empire right from under him and ultimately killing him.

Then to add on more tragedy I'd have him and Lana genuinely be in love but for Lex to discover that he was sterile do to radiation exposure from kryptonite at a young age that would have also made him bald. I'd also throw in Clark to add in a bit of a love triangle Clark would immediately suspect that Lex did murder his father and that would make him do everything he could to get Lana away from Lex and he'd keep digging and find Lex was committing crimes using his money and power to bend the law but from Lex's point of view he'd be doing it for the greater good and he might even be actually saving lives. However Clark can't find any solid proof and he'd do something out desperation and would lie and or make up sources in a story that destroys Lex and makes Lana leave him and temporarily puts him behind bars where he gets sent down a darker path.

Ultimately he grows to hate not only Clark but also Superman because from Lex's point of view there's a double standard while at the same time I can see him hating Superman for the kryponite radiation and how it affected his life and I can see him saying this "I break the law I'm a criminal that vigilante breaks the law and he's held up as a hero!" and when Lex finally finds out Clark is Superman and that the two people he hates more than anything are the same person he finally goes off the deep end and he just becomes consumed with wanting to kill and destroy Clark/Superman.

The reason I like the idea of Clark crossing the line even just to beat Lex especially early on in their history is it would make things interesting between them. Also I remember Lex (well a clone) saying to Clark in Smallville "You always make yourself look better than me by making me look like some kind of monster!" and I'd like their relationship to be written in a way where that's some what true but at the same time for Clark to be some what justified in seeing Lex as a monster.

Ultimately I'd like a confrontation with Superman and Lex where Lex calls him out on lying about the story he wrote and to add the cherry on top it could be revealed the story Clark lied about that ruined Lex's life made Clark's career as a reporter and I'd love to just see Lex make Clark admit to lying or at the very least stretching the truth. Like it comes out Clark discovered Lex was conducting illegal medical experiments and while he didn't know the details he just took that information and ran with it and Lex in their confrontation throws in his face that he was working on cures for things like cancer, HIV, and etc but once Clark's story hit his research was confiscated and he lost everything.

I like that idea because it would be fun to see things reversed where Lex is justified in hating Superman and puts Superman in the hot seat and I'd like to see Superman shockingly confess to lying and for someone to show up unexpectedly like Lois or Jimmy I'd like to see someone he knows react to him confessing that he lied even if it was a "Okay maybe what I wrote wasn't one hundred percent accurate." sort of like this scene. Warning Gotham fans major spoilers.