Well, there's a list of 8 directors in the running, according to Cinematical:
After Bryan Singer dropped out of X-Men: First Class, I expected the rumor machine to kick into high, high gear. But things have remained relatively quiet until today, when Deadline Hollywood Daily and Entertainment Weekly reported that Matthew Vaughn had been offered the director's chair. As geeks remember, Vaughn was once offered X3: The Last Stand, and once held Thor in the palm of his hand. Losing the latter was a huge reason as to why he chose to do Kick-Ass.
However, DHD and THR's Heat Vision are already saying Vaughn has passed. Reportedly, Fox is now looking at Louis Leterrier (who could use it to nurse his wounds over not getting The Avengers), Jonathan Mostow, Daniel Espinosa, and Rupert Sanders. Timur Bekmambetov, David Slade, and Carl Erick Rinsch are also in consideration. Perhaps it might be easier to make a list who isn't up for the job!
The decision will reportedly be made next week, as Fox wants to get X-Men: First Class enrolled by the summer or fall. Personally, I'm hoping for Espinosa or Sanders. (Once upon a Night Watch, I might have rooted for Bekmambetov, but I've cooled on his style since then.) I'd like to see someone fresh come in, and get to make their mark. I still think this is a silly way to return to the X-Men franchise, and giving it to a Hollywood newcomer feels like a good justification for its existence.
-Personally, I'd like to see Rinsch or Slade get the shot, though none of them are particularly great or terrible choices...thoughts?