I voted for, "Setting Book" because Hero really doesn't have one. The Champions Universe is owned by Cryptic (or whoever bought them). A new setting would also be new material, which is more likely to sell to Hero's existing customer base than a reprint of 6e.
What I'd really like to see is for Hero Games to set up a Patreon project similar to what Evil Hat did for FATE. Hero fans chip in a few bucks a month, Hero produces a steady stream of new material, and Hero Games starts looking like a going concern again. (Of course, there's probably some reason why they aren't doing this already, but I am not privy to their reasons.)