My go to subgenre for superheroes is the Pulp era. Don't get me wrong ... I dig the Silver Age stuff too from both DC and Marvel, but those Pulps hit what I call a Sweet Spot in Superhero gaming.
See, most of the Pulp or Golden era characters haven't developed the power escalation that occurred over time. Even the BIG GUY was no faster than a speeding bullet, only as powerful as a locomotive, and able to leap tall buildings in a single bound. But he's the top end of the scale. Same thing with characters like The Black Terror ... kind of a Superman with more ambiguous tendencies. Or how about Doctor Solar, who can literally do just about ANYTHING ... No, what I'm talking about are characters like The Shadow, Doc Savage, Phantom Lady, Dick Tracy, and even Tarzan. These are mortal men - and ladies - of adventure who don't overpower a game into boredom.
My Mystery Men group (see the Downloads page) are kind of a 'Pulp Avengers' and hit the upper strata of the Pulp character Sweet Spot, but really it's not so much about the characters, although they do figure into the equation, it's the adventures/scenarios themselves that really define a Pulp Game. There's a series of Marvel Adventures that works really well with the genre called After Midnight, Night Moves, and Night Life. Street Level Heroes against various mob like groups ... it's a natural. Just gritty it up a little and be sure to check out the vigilante house rules at Classic Marvel Forever.
I'm kinda just freeform blogging here with no real direction, so I'll wind it up ... but there will be more on this later, I assure you.