If you're going to do a Superman collection, a Supes vs. Luthor theme seems like a natural, doesn't it? Luthor is probably second only to the Joker in terms of famous comic book villains, though I think calling him "the most dangerous man on earth" is laying it on a bit thick.
"The Luthor Nobody Knows" by Elliott S! Maggin, Curt Swan, and Bob Oksner
"Superman's Super Hold-Up" by Bill Finger and Wayne Boring
"The Most Dangerous Door in the World" by Cary Bates, Swan, and Jack Abel
"The Luthor Story" is a text-piece by ENB about the Luthors of Earths One and Two
"The Death of Luthor!" by Edmond Hamilton, Swan, and George Klein(I bet that doesn't last)
"The Condemned Superman" by Hamilton, Swan, and Klein
"Luthor's Hammer of Hate" by Bates, Swan, and Murphy Anderson
"Lex Luthor--Super Scalp-Hunter!" by Maggin, Swan, and Kurt Schaffenberger
Weird how the cover proclaims "6 Deadly Duels!", when in fact there are seven stories in this book! Since the first story is an origin story, I guess DC was being extremely honest and not counting it as a genuine Superman vs. Luthor duel. Ah, comics were different then...