You know, all the reviews of "Superman Returns" have mentioned the first two Superman films (the whole "vague history" stuff) and they all say that Superman II is better than Superman 1, that Richard Lester did a better job of capturing the balance between pop art and camp, etc.
Anyhow...
1) Superman 1: The first and simply the best.
2) Superman 2: Good follow up, great fight towards the end, great villain in General Zod and his underlings, but suffers from choppy editing.
3) Superman 3: Suffers from being more of a showcase for Richard Pryor and being to absurd. The idea of Superman turned evil could have made for a fascinating third entry, and Reeve clearly gave his best, but his efforts were thwarted by the film's uneven tone. Worth a rental for the scene where evil Superman fights the good Clark Kent in the junkyard. Plus future "Smallville" mom Annette O'Toole shows up, and she is so damn hot...
4) Superman 4: Once again, this could have been a fascinating film with it's brainchild idea of Superman tackling a global/international issue like nuclear warfare, but a poor budget and off camera mishandling destroyed whatever chance this film had to succeed. Sincere performances from returning stars like Reeve help. Even with an obvious stick holding the flag up on a moon to suggest weightlessness, the way Reeve straightens the flag out, and the look of pride on his face just before he gets tackled by Mark Pillow, he still made me feel and believe in Superman.