Since this is an All Time list, I wanted to push for Kurosawa and Hitchcock.
I know you're all thinking that these are two that don't need any help, but I think that's exactly why they're likely to be forgotten. In order to get Gondry and Nolan and many other currently popular directors a higher rank, it's easy to place these two titans lower than they deserve.
When I was in my early 20's I watched their classics: Seven Samurai, Ran, Rashoman, Yojimbo, Psycho, Rear Window, The Birds, North by Northwest, Vertigo.
Then I dug a little deeper and discovered Throne of Blood, The Hidden Fortress, High and Low, Strangers on a Train, Rope, Shadow of a Doubt, Dial M For Murder
If you remove those films from their filmography, you've still got a lot of great movies to watch. I only recently saw Drunken Angel, Dreams, Red Beard, Derzu Uzala, Marne, The Lady Vanishes, The 39 Steps.
I urge Filmspotters not to leave these two off their list just because they feel everyone else will give them the proper respect. They should be on everyone's list, or else I'd love to read the argument in favor of their exclusion.