I don't really think of Luthor as Superman's "Arch-Nemesis", but as a sort of "Arch-Rival". The reason he's Superman's most
interesting foe to me is for all the reasons he
can't be the arch-nemesis. Superman's arch-nemesis, if I were to pick, would probably be Brainiac.
I get what you mean when you say that Lex is a very human evil compared to Brainiac, but honestly the reason I find him so compelling is that I think on a fundamental level, Luthor isn't evil at all. Arrogant, yes, spiteful, yes, but not evil.
All this isn't to say that Luthor isn't Superman's greatest challenge. He is, because he makes Superman outwit him. If Luthor is a man who doesn't let innocent people die in his schemes (and as we've seen in my "Hall of Heroic Luthors" on the previous page, that was once true [though even at the time, characterization wasn't always consistent]) then the
reason Superman continues to have faith that Luthor could do more good than
he could is because he knows Lex isn't actually a cold-blooded killer of innocent people.
(Contrast the modern convention that Superman just totally hates Lex- much less interesting to me)
Lex, of course, doesn't think he could get enough glory to surpass Superman, so he's totally committed to being the most effective criminal in history rather than the second best hero.
Of course, every time Lex fights Superman, it's a challenge to Superman's reigning status as the Ultimate Cop. It's about showing that Superman is fallible, that Superman can be beaten, that Superman can be
killed, to prove that Superman doesn't really
deserve to be considered the World's Greatest. It sends a message that Luthor > Superman.
He just doesn't need to kill people to get that point across, just like Superman doesn't need to kill to get his point across. If Luthor got away from Superman but a kid died during the getaway, Lex would be a monster. He's too wrapped up in his own image to allow that, so of
course he saves the kid and goes to jail. After all, he can literally escape from jail any time he wants to.
So I suppose I mean that when Superman fights Brainiac, or Metallo, or Parasite, it's a battle for innocent lives who will be lost, but when Superman fights Luthor, it's a battle for ideas and for dominance.
I would really like to just lay out how I see the character seeing Superman's morality, but it's almost five a.m. where I am
and I've had an epiphany. I think I might have figured out our differences regarding the character- we both like Lex, but we like versions so radically different from each other that they're almost irreconcilable:
I cannot bring my ideal conception of Luthor back. He's sort of got the trappings of the World's Greatest Criminal back after losing the trappings of Byrne's Kingpin Lex, but his nobility is now a facade.
Still, the Lex of the late Silver Age stories is still there, in bits and pieces, just like how the Golden Age Depraved Terrorist is still there and the Kingpin Lex is still there, the Silver Age Noble Renegade Criminal is still there, partially. I just wish he was more dominant than he is in the current stories.