There are none that I would never get tired of. I don't often rewatch a movie, but there have been a few.
Dawn of the Dead (remake)
Supertroopers
Reservoir Dogs
Shawn of the Dead
Mallrats
Yes, Mallrats! "That kid is on the damn escalator again!"
Are you a Clerks fan too?
Yes to everything but Throw Mama, haven't seen that in years.
The other four I can quote by heart.
Fight Club! "It's only after we've lost everything that we're free to do anything." I'll put that movie on a couple times a year.
Never seen any of the Alien franchise.
The first is the best. One of the best horror movies ever created, in my opinion. 2 is less of a horror movie more of a really good action movie. 3 goes back to the roots. Dark and character driven. 3 is just for fun, if you really enjoy the franchise.
The Fifth Element, Stargate movies, Fight Club, old Star Wars and Star Treks, X-mens, Good morning Vietnam, Jason Bournes, Jurrasic Parks
I have a few but "Airplane" is by far my favorite rewatch. Seen it over 50 times and still makes me laugh at different stuff every time.