I loved Morrison's synthesis of the mad scientist pre-Crisis Luthor with the corrupt businessman post-Crisis Luthor.
His dissection of Prometheus as the ultimate emo kid is both hilarious and apt (especially given that that's what so many fans and creators mistakenly see Batman as, and since Prometheus is trying to be "the Batman of evil" ...), and yet, Lex is still willing to work with the guy, in spite of regarding him as an inferior, because deep down, there's a part of Lex that's into the GAME of villainy in the same way as Prometheus is ("I'm in this for the buzz").
You can see this in the way that Luthor talks about the Joker here, as well - he KNOWS that teaming up with the Joker makes about as much tactical sense as sticking your dick in a blender, but there's still a slow-motion car-crash fascination there.
Oh, and this was the story arc that convinced me that Luthor and Zazzala were fuck-buddies - as much as Zazzala herself would protest the informality of the term - because of how casual Luthor is toward her, and how much Zazzala insists on asserting her rank over him.