1. Elia Kazan 2. Sergie Eisenstein 3. Clint Eastwood 4. Fred Zinnemann 5. Vincente Minnelli 6. Frank Capra 7. Paul Greengrass 8. Mike Nichols 9. Tony Richardson 10.Alexander Payne or Will Wyler (although I crapped on him in the FYC thread, sorry ). Buster Keaton wouldn't have been a bad choice either
Definitely Sergei M. Eisenstein. Can't believe he didn't make the cut. Without him, I feel like film would be nothing (and not only was he influential, his films were great as well).
The rest of my top ten would be mostly modern as there are a lot of older directors that I just haven't seen enough from to include, but Kenji Mizoguchi & Edgar Wright missing stinks, though I understand why neither made the cut.