I honestly view Lex Luthor as a fundamentally decent man, just one obsessed with praise and adulation. At least, that's how the DCAU Lex Luthor feels to me. The supplementary comics for Superman:TAS say that Lex Luthor grew up poor in the slums. He dreamed of being a rich benefactor to humanity, but his parents always derided his goals. So that inferiority complex sits like a sack of stones right on his chest. He needs the validation of others to feel good about himself, because his family never gave him validation. Now he's a broken man whose hatred of Superman largely stems from him stealing the spotlight away from him.
Lex Luthor hates Superman with a burning rage, but he doesn't hate people. That's evident in his relationships with characters like Mercy Graves and (briefly) Lana Lang. He has positive relationships with people. He donates to charities. He isn't a man who dreams of massacre and rampant bloodlust. He's not that kind of man. He just wants to be idolized. He wants that validation, because he clearly isn't getting it from himself. It's tragic, and Clancy Brown sells every script that the writers give him. He really conveys those equal parts menace and loneliness. The desperate cry of a rich man who never felt love.
I feel like him and superman have more in common than either cares to admit. They like helping people, in their very different ways. They both have public and private identities/faces they show to the world. But while Superman at least has a support system and secret keepers in the form of his parents and childhood friend Lana Lang, Lex has nobody. He doesn't even fully open up to Mercy. Mercy sees Lex as some kind of mentor. But Lex just sees her as an employee. One he's close to, but an employee nonetheless. He's too scared to open up and let her see the real him. Nobody has ever seen the real Lex Luthor. The man that was around before LexCorp.
Lex Luthor is tragic in that way where you still can hate him for his greedy capitalism, but you can also really see the anguish in every lex luthor story. He's always either hurting, angry, or having to deny that the villain of the week was created by him. He's got a great character, and the show could've done with more episodes exploring his life before all his wealth. That would've been fascinating.
