From a historical perspective, it would be Storm. For a long time she was the most prominent, darn near only black superhero I got exposure to. But post-Hudlin/McDuffie/Liss's take on Storm and the Storm/Panther marriage, I haven't cared so much. Don't like they've handled Storm. Though they've never really handled Storm well in comics or in the films. It's just the representation was very powerful to my young eyes. I have picked up the Greg Pak Storm solo series, read a few issues, but need to read the entire run to really judge it. From what I read I wasn't overly impressed.
But I got to say, I've never been the biggest fan of Falcon. Though from what I recall Falcon was the first black superhero seen on the cover of a comic and it was a very powerful image. I've read just a tiny bit of Priest's Falcon/Captain America series, but did buy the whole run and hopefully will get into it one day. Truth be told, Falcon comes off as a bit of a do boy to me, and Anthony Mackie playing him in the films doesn't do much to change that impression-though to his credit, Mackie has done a fine enough job in the role. But I got to say that it's Nick Spencer's current take on Falcon that I've enjoyed the best. It's socially relevant, yet also balances in the superhero tropes you would expect in a mainstream superhero book. I liked it so much I decided to subscribe.
I never thought I would like the Falcon more than Black Panther, but in comparing the current runs, there it is. So, back to the original question, I'm going with Falcon.
