I watched more Elba movies/tv to get a better feel for his American accent.
It sucks in a lot of Prometheus and sucks in The Office, but he sounds perfectly fine in everything else.
Elba is probably the best choice for the role, despite being suggested far too often.
Elba is an actor that would get me excited about John Stewart. Chadwick Boseman is a fine actor, but he's not an actor that will draw me into seeing a movie. Idris Elba on the other hand, is that type of an actor. Perhaps Chadwick will become a draw to me at some point, but that's important to me when fancasting John Stewart. Since I'm not the biggest fan of the character (at least compared to the clearly superior Hal and Kyle

), the actor really has to draw me in, since the character really doesn't interest me all that much.
Elba is the clear choice for John Stewart. If the intent is to make John Stewart the lead Green Lantern, Idris Elba is the best choice by a mile. Sorry but I don't care about Chadwick Boseman enough to get excited about a movie series with him as the star. John Stewart is the third most interesting Green Lantern, so if they give him his own movie series, the actor playing him better be ****ing breathtaking, to make up for the lack of quality character development compared to Hal and Kyle. Idris Elba is that type of quality actor and so is Chiwetel Ejiofor, but Ejiofor is pretty miscast as John Stewart, so Elba is the clear choice.