My ideal Lex is a dude who doesn't want to destroy Superman, he just wants him to back the hell off and let humanity run its course. He views Superman as an impossible standard for people to live up to and he thinks that they'll become complacent and stop trying to improve because of Superman. I had one thing I wrote where he says, effectively, "someone trapped in a burning building might be able to walk right out the door, but they'll be content to sit and wait and, possibly, die, while waiting for you to arrive." He knows everything about Superman, he feels bad that his planet was destroyed, but views his refugee status as a sort of unnatural affront to the natural path humanity was already on. Whether or not humanity needs to be saved, it's up to them to do it, not Superman, and, frankly, he's entirely content to allow Clark Kent to live his life and write his stories.