In no particular order:
It's a Wonderful Life - an undisputed classic. Daughter (20) and i still string popcorn and cranberries and watch it as we get Christmas.
True Romance - Not directed by Tarentino, but I believe the script was written by him. One of the best casts with amazing characters.
Raising Arizon - First Cohen Bros movie I saw. There are some many great hidden gem lines that it is a watch and find funny every time.
The Big Lebowski - Speaks for itself. Nothing like dropping a line from it while playing golf with the Counting Crows and they bust out a J
Empire Strikes Back - Love all the Star Wars content, but there was something about the darkness of Empire when seeing as a kid left an impact that puts it at the top.