Both lifetime and last 5 years Lifetime -- Dr Strangelove Last 5 yrs -- Serenity * my lifetime most watched is more accurately the Wizard of Oz because of childhood and TV replays. Xmas story and it's wonderful life are also high up there but only because of ease of access to watching them once a yeat
Lifetime Pulp Fiction and Donny Darko. Last 5 years Django Unchained and This is the End. I smoke the weed.
Movies I seem to watch over and over, for no apparent reason: 21 and 22 Jump Street Starship Troopers Secret Life of Walter Mitty
Star Wars Episode III I watched it six times in the theaters, and I watched it a ton when I downloaded it shortly thereafter. I actually can't watch it anymore.
I used to have a habit of falling asleep watching episodes of MST3K, so one of those more than likely. Probably Space Mutiny.