Throughout his career, Ebert maintained that the greatest film he had ever seen was Orson Welles’ magnum opus. He reflected: “Reading the many accounts of Citizen Kane is a little like seeing the movie: The witnesses all have opinions, but often they disagree, and sometimes they simply throw up their hands in exasperation.
“And the movie stands there before them, a towering achievement that cannot be explained yet cannot be ignored. Fifty years later, it is as fresh, as provoking, as entertaining, as funny, as sad, as brilliant as it ever was. Many agree it is the greatest film of all time. Those who differ cannot seem to agree on their candidate.”
Source: Roger Ebert names his 10 favourite films of all time