Cameron: The Terminator, Aliens, Terminator 2: Judgment Day, Avatar
I don't like most of his work very much aside from the two Terminator movies and True Lies.
Capra: It Happened One Night, Mr. Smith Goes to Washington, Arsenic and Old Lace, It’s a Wonderful Life
All of the movies of his I've seen are good (haven't seen "Smith"), but I can't stand Jimmy Stewart. That's not his fault, but it makes his work harder to enjoy.
Chaplin: The Kid, The Gold Rush, City Lights, Modern Times, The Great Dictator
Have only seen two of his movies, but they were both amazingly original, thoughtful, and entertaining. I don't think I've seen enough to really rank him, though.
Coppola: The Godfather movies, The Conversation, Apocalypse Now
Way overrated. I like "The Godfather" movies, but I despise "The Conversation", "Apocalypse Now", and "The Outsiders" - three of the slowest, most grating movies I've ever seen, with poorly developed characters that I couldn't care less about.
Eastwood: Unforgiven, Mystic River, Million Dollar Baby, Letters from Iwo Jima, Changeling, Gran Torino
Haven't seen many of his movies (not even "Unforgiven"!), but I don't know if I can ever 'forgive' him for what a shitty, overrated melodrama "Million Dollar Baby" was. It started off as a solid boxing movie, then a twist turned it into a corny pile of crap.
Hitchcock: The Lady Vanishes, Rebecca, Shadow of a Doubt, Notorious, Rope, Strangers on a Train, Dial M for Murder, Rear Window, Vertigo, North by Northwest, Psycho
I've only seen "Psycho", "Vertigo", "Rear Window", and "North by Northwest". I liked them all except "Rear Window", which I found technically impressive, but unable to overcome Jimmy Stewart's annoyingness. He deserves a lot of credit for making some of the most watchable Jimmy Stewart movies thanks to the dependably consistent direction and writing in his movies, but they generally lack the amount of heart I need to appreciate movies most. Still, can't fault him for that, and would consider him one of the best, at least objectively.
Kubrick: The Killing, Paths of Glory, Spartacus, Dr. Strangelove, 2001: A Space Odyssey, A Clockwork Orange; Barry Lyndon, The Shining, Full Metal Jacket
I have seen most of his movies and found them all enjoyable and enthralling, but other than "Dr. Strangelove", "Full Metal Jacket", and "Paths of Glory", they left me a little cold. They're all excellently directed with interesting characters, but they're hard to watch since they're so twisted and disturbing. It makes him feel like a bit of a one note director, like he's just obsessed with the dark and ugly side of humanity, which is okay, but I think the best directors can look at it from different angles instead of just sticking to one.
Kurosawa: Rashomon, Seven Samurai, Yojimbo, Ran
Have only seen "The Seven Samurai" and "Ikiru" and so far I don't understand the hype. They were both too long, dull, and full of characters bitching and crying. A few beautiful shots, but no characters or stories I could really get into.
Leone: For a Few Dollars More, The Good, the Bad and the Ugly, Once Upon a Time in the West, One Upon a Time in America
Hard to say. Couldn't get into "The Good, the Bad, and the Ugly", and haven't seen his other movies, but it seems like I'm just not a fan of Westerns. Have yet to meet a 'classic' Western that I liked.
Nolan: Memento, Batman Begins, The Prestige, The Dark Knight
His movies are all good, but it's too early in his career to judge whether he's one of the all-time greats. Also, other than "Memento" (which I feel is just about perfect), I think most of his movies have major script problems that detract from his fantastic directorial skills and his obvious ability to always get great performances out of actors.
Scorsese: Taxi Driver, Raging Bull, Goodfellas, Casino, The Departed
I love all of his movies that I've seen (which includes all of the ones above), but like Kubrick, his movies are a little too obsessed with the dark side of human nature sometimes, and that makes it a little hard for me to embrace them fully.
Spielberg: Jaws, Indiana Jones movies, Schindler’s List, Saving Private Ryan
The above listed movies are all terrific (although I don't know about Indy IV, since I haven't seen it), but he's made too many bad ones to be considered the best. For every one of those listed above, there's a stinker too.
Tarantino: Reservoir Dogs, Pulp Fiction, Kill Bill movies, Sin City (as "special guest director" only), Inglourious Basterds
I like all of his movies, but after "Inglourious Basterds", I realize he's the most repetitive of all directors and his schtick is wearing thin. I give him credit for basically creating a completely unique style of movies with the way he writes dialogue, homages other movies, sets up shots, uses music, etc., but he's starting to seem formulaic, and the best directors need to show some ability to expand and be innovative in their filmmaking.
Wilder: Double Indemnity, Sunset Blvd., Stalag 17, Witness for the Prosecution, Some Like It Hot, The Apartment
This guy is my favourite in the whole list. He worked with some of the biggest stars of all time in Hollywood and guided them to some of their career best performances and worked in several different genres, hitting it out of the park in every single one. He's the most versatile of all the directors listed and while other directors' work may be familiar mostly because of affinity for certain themes, genres, and styles of direction/writing, what makes his work most recognizable is simply how excellent and polished it always is in direction, writing, and acting.
So from an objective standpoint, I think Scorsese is the best director on the list, since he's the one most consistently able to make movies that feel important and are top of the line in terms of all the elements that make movies work (direction, writing, etc.), but Billy Wilder is just as consistent and a little more versatile in terms of the range of themes and genres he covers and his movies make me happier, so I vote for him, allowing my subjective feelings to influence my ultimate opinion. Nice list, by the way. I think it should have Sidney Lumet too, but otherwise, it's very thoughtfully put together.