On the one hand, I can think of a lot of extant heroes that I think would translate well to TV or movies. OTOH, I think it is too easy to screw up a Supers genre show/movie, and wouldn’t want to see many of them warped that way.
It might be interesting, though, to see some more done a la Mutant X, where the characters and situations are similar to but not quite the same as the world of the characters we know. Like the Elseworlds line, or versions of the characters from other dimensions. Hell, an Elseworlds series could be fun. They could do it AHS style, even, with the alternative characters being given a miniseries or whole season.
DC did OK with Gotham By Gaslight. 1602 was cool. A storyline in which a Merlin-esque figure uses the powers of the original Green Lantern or Starman devices could be cool.
Then there are characters like Adam Strange, who could really fill the void of series like Flash Gordon or the old Commando Cody serials.
Or imagine all the stories that could be told about the Legion of Super Heroes. Or involving the Kree, Skrull & Shi’Ar empires.