Lex Luthor - Man of Steel: This five issue mini-series offers a different look on the character of Lex Luthor. It explores the motivations behind why Lex is against Superman. One of the best Lex Luthor stories to date.
Forever Evil: While not entirely centered around Lex Luthor, he is still very much a large part of the story. The evil Earth-3 variant of the Justice League, the Crime Syndicate, invades Prime Earth in an attempt to take it over. This story explores Lex's more heroic nature and helps counteract the cold-blooded villain persona that he is so often portrayed as.
All-Star Superman #5: Clark Kent and Lex Luthor spend some prison time together in this issue of All-Star Superman! This story helps humanize Lex and, much like the others, help readers see that he's not entirely evil.