Mostly feelgood+comedy stuff like the Back To The Future trilogy, Planes, Trains and Automobiles, Home Alone 1&2, National Lampoon's Christmas Vacation and even The Wedding Singer.
Some pure comedy stuff, Holy Grail, Life of Brian, Blazing Saddles, Airplane 1&2, Naked Gun1-3.
Some action stuff like the Star Wars original trilogy, Die Hard 1-3, LOTR and the first Matrix.
The odd purely feelgood movie like Shawshank, Good Will Hunting and It's a Wonderful Life.
I've even rewatched stuff that seems pointless, like Sixth Sense, The Ring, Memento, Identity and The Butterfly Effect, just to see how they kept me guessing for so long. That's MY ocd, having to pull stuff apart to see how it works, even if it breaks.
If I had to name just one though, it would probably be Die Hard.