This list changes a lot, mainly after i've seen a movie by one of the people listed below, they often move up in the rankings, but i'll try:
1.Federico Fellini
2.Akira Kurosawa
3.Francios Truffaut
4.Martin Scorsese
5.Ingmar Bergman
6.Jean-Luc Godard
7.Luis Bunuel
8.Paul Thomas Anderson
9.Billy Wilder
10.Robert Altman/Stanley Kubrick/Fritz Lang (can't decide)