Complete reboot. No protracted origin story - just have the credits sequence be a montage that shows the origin. Once the credits are over we immediately dive into the action with Superman as an established superhero in Metropolis.
Lex Luthor is a great villain, but he's been used too much in Superman films and TV shows. The character needs a rest. Perhaps you could establish - maybe in the opening montage - that Superman has exposed Lex as a villain and sent him to prison. Oh, and for the opening montage I wouldn't have footage of Superman in action, nor of him in the suit. I'd show the destruction of Krypton, the Kents finding baby Kal-El, young Clark's powers kicking in as he grows up in Kansas, Daily Planet headlines about Superman's debut, reaction shots of people watching Superman in action, etc, but I'd keep a full view of Superman in action for an opening action sequence following the credits.
I'm open to a Superman film with a contemporary setting or a period setting (although I doubt the studio would ever make the latter), but if it was a period setting I'd go for the late 1930s rather than the 1950s.
Whatever the time period, Superman films should have a tone and setting that allows for science fiction villains and outsized action.
Villains:
Film 1: Brainiac as the main villain; Metallo and Parasite as henchmen villains.
Film 2: Darkseid and the legions of Apokolips.
Cast: maybe Henry Cavill as Superman/Clark Kent and Mary Elizabeth Winstead as Lois Lane (if the film was shot in 2011 they'd turn 28 and 27 respectively in that year).