I think of mechanics that support setting/genre and there are only a few that I like and am willing to play.
Brave New World, L5R, 7th Sea, Call of Cthulhu, Chill (Pacesetter and Mayfair Games editons), Cyberpunk 2013 and 2020, Earthdawn, Shadowrun, Star Wars d6, Torg, oWorld of Darkness, Warhammer Fantasy all have great settings. I would and/or have purchased products for all of the above with the exception of Brave New World, but you could not get me to play any of them due to the system mechanics.
There are settings for pre-3e D&D. I like Al Quadim, Birthright, Dark Sun (pre-revised), Forgotten Realms (pre-3e), Greyhawk (folio and boxed set), Mystara/Known World Gazetteers, Ravenloft and would run under other systems, but not under pre-3e D&D rules.
Then there are the Corex+ games (Marvel, Leverage, Smallville). I admire the design and want them on my shelves, but they are not my style to run or play. I think Spectrum Games's Capes, Cowls and Villains Foul and their Cartoon Action Hour Season 2 are going to fit into this category as well.
Now, I would run any of the settings above with Savage Worlds, Cortex (classic), a slightly house ruled Cinematic Unisystem, True20 (if wanting a level/class system) or, for super heroes, Mutants and Masterminds 2e