The winner is The Wizard of Oz. Your grandmother or your great grandmother knows quotes from it. If she’s really cool, she might know some from Airplane or Monty Python and the Holy Grail (which were the first two that I thought of) but she will definitely know where “There’s no place like home” and “We’re off to see the Wizard” are from.
And “We’re not in Kansas any more”, “And Toto, too?”, “Surrender Dorothy”, “Follow the yellow brick road”, “Are you a good witch or a bad witch”, “What about Dorothy?”
I think there’s a difference between “quotable” and “recognizable.”
I cannot even tell you how many situations have lent themselves to a quote from The Big Lebowski. Something about that movie’s script gives it an ability to be adapted to almost any situation.
The Wizard of Oz, Gone With The Wind, The Godfather, Star Wars and Casablanca are probably the most recognizable, but most of the iconic lines from those movies only work in a few specific situations.
Not nearly at the top of the list, but I’ll throw in an honorable mention for Real Genius:
“There are lots of decaffeinated brands that are just as tasty as the real thing.”
“Don’t you know that eating that stuff can give you very large breasts?” [looks down] “Oh, my God! I’m too late!”
Hathaway: I want to see more of you around the lab.
Knight: Fine. I’ll gain weight.
“This? This is ice. This is what happens to water when it gets too cold. This? This is Kent. This is what happens to people when they get too sexually frustrated.”
"I was thinking of the immortal words of Socrates, who said, “… I drank what?”