Always loved this series, and this scene in particular. The balancing between the fact that Luthor openly admits loving himself "first and foremost", and that he can actually experience true, selfless love such as that for his daughter or for Lois, works really well for me. I like to think that's how real humans are; our biology demands that we value ourselves above everything else in the world, no matter how hard we may try to hide from that fact (Luthor, of course, has no need for self-deception--he acknowledges and embraces his animal nature), and yet we are also capable of valuing others to such a high degree that we can move beyond our biological imperative to survive and put their survival above our own. In that way, you could say that Luthor and Superman represent those two aspects of the human psyche.
Danger: Psychologist Reading Comics, Beware Of Possible Overanalysis