Of the three, Vaughn seems like the easiest fit; he’s directed a number of superhero movies (Kick-Ass and X-Men: First Class), and his Kingsman was a) a hit, and b) the sort of light action fare that might comfortably fit Barry Allen’s quick-moving antics. (Minus some of the head-popping gore, anyway.) Raimi’s a weirder choice; although his Spider-Man movies helped kick off the superhero movie boom, he hasn’t had a hit since 2004’s Spider-Man 2. (That being said, his signature first-person POV shots seem like a natural fit for zooming around Central City.)
According to THR, though, Zemeckis is the frontrunner; his love of big technical showpieces—Forrest Gump, The Polar Express, the plane crash sequence in Flight—making him a squint-and-it-makes-sense fit for a movie that will live or die by how it captures The Flash’s fast-forwarded action. That being said, it’s been a minute since Zemeckis successfully operated in big blockbuster territory, with recent films like Allied and The Walk making less-than-superheroic impacts.
Of course, it’s always possible that this is just a smokescreen, and that Warner Bros. just brought in a trio of recognizable directors to build up fresh buzz for a would-be tentpole that’s fallen to the wayside. We’ll know more if and when the studio actually names a director for The Flash, instead of just flirting with various famous candidates for the job.