Via "Complications Ensue", a link to the Sight and Sound Top 10 Movie Poll, which they hold every ten years. You can also see the individual top ten lists of various directors.
Going through each director's personal top ten list is fun, but one thing that also interests me is just the history section, detailing the results of the poll since Sight and Sound started polling critics in 1952. The 1952 poll consisted entirely of two categories of film: European films and American silent films. There were no American sound films among the top ten. At the time, it was pretty much gospel among international movie critics that the American film industry had gone into creative free-fall after sound came in, and accordingly the only post-1930 American film worthy of inclusion was Chaplin's mostly silent City Lights.
Ten years later, 1962, the results have changed a little. Now there's one Asian film on the list (Ugetsu), and one American sound film, Citizen Kane, which as a matter of fact has climbed up to # 1 on the list when it wasn't on the 1952 list at all. Notice also that Chaplin has dropped off the list altogether, after having two films on the 1952 list.
In 1972, there are a whopping two American sound films on the list: Kane and, at # 8, The Magnificent Ambersons. Apparently it was okay to pick Welles, but only Welles, if you wanted to pick an American sound movie. Note, however, that Renoir's The Rules of the Game is up to # 2 and Chaplin has been replaced on the list by Buster Keaton (The General).
But in 1982, the increasing critical respectability of American sound movies finally made a breakthrough in the poll. Now Kane and Ambersons have been joined by Singin' in the Rain (a movie that celebrates the death of the silent film and the coming of sound), The Searchers and Vertigo. On the downside, movies that are not American or European are absent from this list.
In 1992, you can see the influence of the increasing critical favor towards the film-brat generation of the '70s, with the Godfather movies and honorary '70s movie Raging Bull supplanting lighter fare like Singin' in the Rain. Also, Japan makes a comeback with two Kurosawa films tied for the # 10 spot -- and Chaplin supplants Keaton again, but with the "edgier" Modern Times.
In 2002, the most recent critics' poll, Kurosawa is (surprisingly) absent, with Ozu representing Japanese films instead; Kubrick's 2001 jumps onto the list, perhaps reflecting a new generation of critics who took enough drugs to make that movie enjoyable. Singin' in the Rain is back, and Vertigo is up to the # 3 spot. Note also that Ambersons isn't anywhere close to making the list now; instead Touch of Evil is the Welles film that comes the closest to making the top 10 (it was tied for # 11), reflecting the change in critical consensus and the general fact that Albert Zugsmith movies are cool.
All in all, while no poll is ever going to produce a top ten list anywhere close to my own, and future lists will probably find more non-American, non-European movies turning up on the lists, I think that in general critical tastes have improved since 1952, when you couldn't be a critic if you believed that there had been any movie worth watching since the stock market crashed.