Favorite: The Schwartz Era - 1971-1986 A period that broke Superman's status quo, and depowered him, then turned around and embraced it, powering him back up, and then turned around again and gradually matured the stories and characters.

Second place: Siegel and Shuster Era - 1938-about 1941 The original crusader Superman who, more often than not, took the law into his own hands to fight injustices that the law couldn't/wouldn't.

Third place: The Byrne/Jurgens/etc. Era - 1986-1999 Superman was brought back to basics, removing some of the more fantastic elements, giving new twists to others, and returning him to his roots, while updating him for the 80s/90s. A tight continuity was formed, becoming a weekly story, Lois and Clark got engaged, Superman died and returned, and Lois and Clark eventually married.