Maybe it's just coincidence, but the most creative periods for the movies seem to occur about every 30 years, usually triggered by the advent of some new technology. First came that short burst of experimentation by people like Georges Méliès during the last few years of the 19th century, right after the medium was invented. The latest is the digital revolution that started around the turn of this century, making it possible for almost anyone to make a movie (and enabling a whole new level of intimacy between filmmaker and subject) by eliminating the need for expensive film processing and slashing the cost and size of professional-quality cameras. But my favorite golden age is the one that stretched from the late '20s to the early '40s in Hollywood. Old pros who'd cut their teeth on countless shorts showed us what could be done with silent film while upstarts like Howard Hawks and the Marx Brothers played with synchronous sound, that shiny new toy, in movies crammed to the brim with fast, funny talk. That probably explains why half of my 10 favorites were made during a 14-year period that ended as WWII began.
The General (Buster Keaton, 1926). The world was a much slower place in 1926, and filmmakers tended to draw things out far longer than they do now. But Buster Keaton's pacing, which probably felt breakneck at the time, still holds up four generations after its debut. The General opens with a sweetly funny, narratively economic setup that moves at a deceptively leisurely pace until we know everything we need to understand about our hero and his situation. Then we hurtle into the almost nonstop action of the rest of the film, which Keaton co-wrote, co-directed, and co-edited. There's great comic timing in these edits, along with a genius's understanding of his still-new medium.