My first superhero RPG was Chaosium's
Superworld in 1984 or thereabouts. Since then I've sampled almost everything in the genre.
A lot of supers games are more wargame than rpg, with a big emphasis on fighting, and complex mechanics for handing a wide variety of interactions.
Superworld and
Champions fit into this category, but I've always found them to be overwrought, and appeal to a certain kind of min-max player.
I lean towards lighter games to get out of the trap of constant battles, and move towards a more narrative approach. Obviously the '80s-era
Marvel Super Heroes RPG was a step in that direction. But honestly, I always felt that
Golden Heroes (still around in the form of Simon Burley's
Squadron UK, which you can find
here) is one of the best of that early era. At least fights were swifter, and it gave a lot of throught to the metagame structure around the fights.
Of the more recent systems I feel that
MASKS does some really interesting things with narrative storytelling is certainly pushes closer to my ideal. The
Sentinel Comics RPG system is at the crunchier end, with a dice pool mechanism that might tax players suffering from brain fade at the end of an evening session, but otherwise does a lot of really interesting things, particularly with regards to integrating the environment into contests.
However, although systems like the Cypher System's
Claim the Sky, the
Marvel Multiverse Roleplay Game and
Savage Worlds Superpowers Companion all have good things to recommend them (even if they are still a bit fighty) I'd probably run FATE's Venture City as my personal preference. It's FATE, it's focus is storytelling, you are less likely to get bogged down in dreary, dragged-out tactical battles.