Don't get me started on this topic!!!!
Instead of going by films I'll just list directors & stuff for now....
Stanley Kubrick - ANYTHING!!!!! But particularly The Killing, Paths Of Glory, Dr. Strangelove, 2001, Barry Lyndon & The Shining.
Alfred Hitchcock - My all time favorite of course, check out Stage Fright - a very underrated film from one of his supposed "off periods". Also very high marks to Frenzy, his last brilliant film.
William Wyler - For some reason his name isn't familiar to alot of movie buffs but this guy was a master in just about any genre.
Howard Hawks - LOVE THIS MAN!!! One of the best directors of comedy & action films ever, can't pick a favorite but His Girl Friday would be way up there...
Preston Sturges - BRILLIANT BRILLIANT BRILLIANT!!!! Miracle Of Morgans Creek is one of the funniest films of all time....
Val Lewton - Anything from the entire series of 40's films he produced, I Walked With A Zombie is a masterpiece of mood...never quite duplicated.
Jacques Tourneur - Great suspence/noir/horror director. Fave films include I Walked (listed above), Out Of The Past (one of the best noir films ever) and Curse Of The Demon (one seriosly creepy horror flick).
W.S. Van Dyke II - Ah...The Thin Man & numerous other 30's screwball comedies give this guy a big thumbs up in my book.
Robert Wise - Just take a look at this guys filmography on IMDB, plus he's still alive and kicking!!!!!
Too many others to mention....
Here's one fave film though that not a whole lot of people know about....