I've done this before, but tastes evolve...
The top two, which are always on the list:
The Apartment (Wilder, 1960)
The Man Who Shot Liberty Valance (Ford, 1962)
And then, these ones are usually vying for the other three spots:
Brief Encounter (Lean, 1945)
It's a Wonderful Life (Capra, 1946)
12 Angry Men (Lumet, 1957)
8 1/2 (Fellini, 1963)
Who's Afraid of Virginia Woolf? (Nichols, 1966)
Raiders of the Lost Ark (Spielberg, 1981)
Ratatouille (Bird, 2007)
Inglourious Basterds (Tarantino, 2009)
And, well, adding those 8 to the first 2 is, at the moment anyhow, probably my Top 10, at least for a Top 10 in which no directors are repeated. And I don't think there's a single actor repeated from one film to another, interestingly. And note that fully half of them are from the same 10 year period, from 1957 to 1966.