I don’t really have a favorite supers RPG. I played a bit of the TSR Marvel Superheroes RPG back in the day, but it never really grabbed me, nor did its contemporary DC counterpart. I tried Mutants & Masterminds (2nd edition), too during the height of the d20 System years. I found it to be supremely flexible, but difficult to grok; I literally needed a spreadsheet for character creation. Plus, I always had trouble with the age old dilemma of “Are the characters secondary to the ‘famous’ supers of the universe or are they brand new supers no one has heard of.”
I also find it hard to come up with character ideas that aren’t just expies of established comic book characters. Even my longest running City of Heroes (an MMORPG) character was basically a version of Iron Man (Atom Man! A scientist shrunk by atomic rays and used dark energy to power his supersuit… or something like that; it’s been YEARS, so I can’t remember the backstory I had for him). Basically, I was playing Iron Man years before Robert Downey, Jr. was. I’m the ORIGINAL HIPSTER IRON MAN. Well, Iron Man crossed with Ant Man. Without the ant-controlling powers. And the alcoholism. And the domestic violence.
You know what? Atom Man was BETTER than Iron Man and Ant Man combined!
I had pretty good luck with using Fate Accelerated to run a Saturday Morning Superheroes game. Granted, the “heroes” I used were characters like Captain Caveman, Casper the Friendly Ghost, Yogi Bear, Hong Kong Phooey, Grape Ape, and The Smurfs (all of them as a gestalt character).
On the horizon, is the Sentinels Universe supers roleplaying game. I’ve played Sentinels of the Multiverse exactly once (and once on my Kindle Fire, but I got my ass kicked by the computer), but I liked it a lot. So, I’m looking forward to what they do with it.
The first full-length novel I ever wrote was a near-future supers novel. I ought to revise that someday and publish it. I need a snappier name than The neXt Generation, though (and a new ending).