Well George Lucas isn't working anymore one can only hope for more Star Wars films, maybe Force Unleashed 501st or, my favorite, a Boba Fett film either or the question stands who should direct I have come up with a few choices that I hope will be beneficial.
1. Ridley Scott
He has done space films such as Alien and Prometheus, he has also done Blade Runner and there is no doubt he is a fantastic director.
2.Christopher Nolan
I know i will be frowned upon for being a nolanite and this might be why I picked him but he always delivers in his movies and has shown a great love for Star Wars
3. Peter Jackson
A fanboys wet dream Peter Jackson has made films that everyone loves from Lord of the Rings to King Kong and each film keeps you on the edge of your seat just like old fashioned Star Wars
4. Neil Blomkamp
thanks to headlopper for this choice, he directed the wildly good District 9 and I think he would be well perfect for a movie about the 501st
5. James Cameron
who wouldn't want this he is such a big director and Star Wars is such a big franchise I think they would fit together like a puzzle.
6. Josh Trank
I just got back from seeing Chronicle and if he isn't busy with Fantastic Four I think this would be just fantastic.
7. Michael Mann
He is a fantastic director but most would think not for Star Wars but I mentioned a Boba Fett movie and that, I'd assume, would be all about mercenaries and the "space mob" and he captures those elements so perfectly.
So tell me what you think in the comments section and I will try to respond to everyone.