Here are my rankings:
1. Man of Steel -- An unmitigated masterpiece and tour-de-force.
2. Batman v Superman -- A slow and difficult middle section cannot overturn the brilliance of the first and final acts.
3. Superman: The Movie -- The standard by which all other superhero films were judged for 30 years, today it plays a bit dated, even corny, but it still beautifully captures the warmth and strength of the character and his milieu.
4. Superman II (Original Lester/Donner version) -- Campier than I might prefer owing to Lester's silly sense of humor, it's nonetheless a well-crafted and vastly entertaining movie that competently captures the characters.
5. Superman II (Donner's recut) -- Oh, what might have been! The Brando material and the Zod trio fight footage make this a must-see for any Superman enthusiast, but the unfinished scenes, the truncated Niagara Falls section and the world-turning redux undermine the excellence.
6. Superman Returns -- A few magnificent scenes are tragically outweighed by some poor creative decisions, including a too-young Lois, a "meh" Luthor, a super-skinny Superman in tiny low-slung shorts, and various other issues.
7. Supergirl -- As charming as it is unconvincing, the film is at the very least good fun. The lead actress is the best thing about this noble failure.
8. Superman III -- A goofball mess of a would-be comedy.
9. Superman IV -- One of the worst films of the 80s, with wretched effects and cornball dialogue.