Kurosawa, Kubrick, Spielberg, Oliver Stone, Brian De Palma, Terry Gilliam and Hitchcock are up there... then there's a bunch of directors that hasn't done that many movies over the years, but some of the great ones... Jonathan Demme for example, after Silence of the Lambs he wasted time doing rock videos... he should do greater things.
David Fincher is still young, I got great hopes for him
Christopher Nolan, even younger... is an interesting director for sure.
Luc Besson should direct more... instead he waste his time as a producer...he's doing the FOURTH "Taxi" movie...(I've only seen the first one...) why someone who directed The Big Blue and Nikita would waste his talent on that I'll never know...
Ridley Scott has done some great movies over the years... and some not so great
And what ever happened to Michael Cimino ? He did Deer Hunter in 1978... and then nothing good after that, only a half dozen movies in total...