Admittedly I will preface this by saying, I have not fully read through this thread. But I had an Ares spin up and an address but no solid ideas until I was reading over the other superhero thread and was reading all the people wanting to do an OC thing.
My current intention was to just do FS3 with the Traits system - but I'm willing to read over some of the options presented here, though I'm no coder so I'd need an assist or I'd use the RPG plugin for Ares.
The current theme I was going for is that there's a town in it's own little pocket dimension where the majority of superheroes lives/train/etc. There's non superheroes that live there also and help coordinate where assistance is needed, etc. You can fast travel from the town to anywhere on Earth.
You would be able to play any Tier from Street Level to High Powered, or even one of these Vital but Mundane 'Background Supports' (Think Cecil from Invincible or Agent Coulson from Agents of S.H.I.E.L.D).
You could be a student/faculty at the school, be a part of the SHIELD-esque agency, or the relief team, run a business in the town, or do whatever else it is you want to do. There wouldn't be an initial overarching metaplot, but instead a 'villan of the week' sort of thing, with each week focusing on a different tier of character.
If this sounds like something people would be interested in, then I'll review some of the other systems presented here and start working more fully on it.