Honestly, it wouldn't be a bad idea to workshop some of our ideas. Following your lead:

While I don't have a specific plot hook in mind just yet, I wouldn't mind taking another crack at the 'Marvel Knights' concept. All stories would be contained to the Marvel version of New York, with street-level to block-level heroes and anti-heroes. One thing I was considering would be instead of having GM-ran events, players could get a one-shot arc of playing as a villain, driving plots without needing the GM to railroad everything. I figure NY is contained enough to encourage people to start bumping into each other, but also big enough that there's plenty to do if you wanna do your own thing.

If we wanted to veer to DC, the same could apply with Gotham City, but that runs into the issue of everything tying back to Batman.