I think that you could do a GREAT Black Lightning movie, and it would be even greater if you included Static as well. And not in some way of them being related, but the way Macduffie wanted to have BL on the show originally. Static had a father on the show that was an invested and caring parent, so I wouldn't want to see the father thing, but the idea of the truly veteran black superhero with a kid who has similar powers but a different generation's outlook could be cool.
I prefer Hal, but a John Stewart GL film could work.
I think MR. TERRIFIC could be great too. Especially if you work in the legacy aspect. I mean, here's an African-American superhero that's super cuz he's super smart. I could see him on screen as a sort of more action-y take on Cosby's character from the I SPY show. Plus he's got the tragic death of his wife and unborn son thing. And his standing as an atheist superhero puts him over the top for me. Just... No T mask. It's the one part of the overall design that looks ridiculous to me.
I think that Vixen could also be cool, but I'd play up her dichotomy of being this in demand model and a superhero. That could be both fun and funny if done in like a JLI way on the big screen.
And even though we are getting a Luke Cage tv show, he could have been a solid film series to my eyes. Sweet Christmas, he should have been up there with Danny a long time ago.
And of The King of Wakanda has oodles of screen potential.