I've got a few of these I think, though my list is shifting a bit more rapidly nowadays because I just watch way too many movies... Just a few of the ones that come to mind from the past (I don't know if I've watched all of them 25 times, but definitely many, many times):
Star Wars OT: I was completely obsessed with this in elementary and high school to the point where I designed my own "C-Wing" starfighter and started writing fan fiction. When I first got going with 3D studio max, the first big thing I drew was the C-Wing, and it was also one of the first thing I printed with my 3D printer. At several points in my life I could literally ramble off all the dialogue in the entire trilogy verbatim if anyone had asked.
Back To The Future (mostly part one, but I've seen all of them many times): I watched this one week and then star wars the next week at an elementary school friend's house. I never knew it could be this good! I think they are what got me hooked on movies.
Jurassic Park (and probably 2, 3 as well): I got tickets to see this as a present for Sinterklaas. We do surprises (French pronunciation) at Sinterklaas, which are basically art-and-craftsy ways of wrapping your presents. My uncle made a paper maché T-Rex and gave it to me with his Nigerian sword that I'd been eyeballing whenever I was around his apartment. I was way into dinosaurs long before Jurassic Park (one of my early memories is a composite made up of going to the local geological museum dozens if not hundreds of times - that museum has been absorbed into much larger Naturalis now, but I still miss it), but it definitely fanned the flames of that obsession for years and years. Best Sinterklaas ever.
Indiana Jones OT: How could you not love an archaeologist who kills Nazis.
The Ninth Gate: This movie somehow just perfectly captures the atmosphere that I tend to be drawn towards. When I used to smoke, I smoked along with Johnny Depp, which left my room filled with a thick cloud of smoke by the end of it.
Aliens: One of the first movies I saw that could be classified as "scary". Still one of the best SF/Action films ever made.
Evil Dead II: Something about a spooky cabin in the woods. Also the gore is hilarious.
Tremors: This is just such a feel good horror comedy.
Groundhog Day: I guess I'm a sucker for repetition.
Eurotrip: I watch this movie (and some other teen/college comedies like Road Trip or Sex Drive) whenever I feel a little trapped and I need the illusion of a sense of liberation.
Revenge Of The Nerds: What can I say? I'm a nerd, and I hold a grudge. This movie works out well for me.
The Dark Crystal: As kids, when my sister and I would stay with my aunt, we'd get to pick a video rental that we'd watch from our fold-out couch bed in the morning. We'd literally always pick The Dark Crystal.
The Labyrinth: I loved this as a kid and as a teen. Totally had a massive crush on Jennifer Connelly
The Holiday: I had a long romcom phase a few years back and this was one of my favorites. It's pretty cheesy, but that's kind of what I was looking for. I often watched this back-to-back with Definitely, Maybe.
The Secret Of My Succe$s: When I was in the same phase, but more in the mood for eighties movies.
The Birds: One of my first Hitchcock movies, and still one of my favorites.
Rear Window: Ditto.
Braindead: The gore. Oh god, the GORE!
The Bourne Identity (the new, not the old one): Just one of my favorite action movies.
And a few that have made my go-to list more recently that will probably reach that mark eventually:
Some Lynch movies that I watch a lot:
Blue Velvet: I like how this is not quite as insane as some other Lynch movies, so while surreal, it still feels realistic.
Lost Highway: I like how this is completely insane (like many other Lynch movies), so it feels very surreal and dreamy.
Twin Peaks: Fire Walk With Me: The extended fan edit is definitely worth watching because it explains some things a lot better, but I think I prefer the original, weird, Lynchian cut.
Let The Right One In: I just think this is a beautifully made film.
The Troll Hunter: I often make a Scandinavian fantasy night of it with this and LTROI.
Only Lovers Left Alive: I dislike some of the dialogue for its pretentiousness, but the atmosphere is as good as the one in the Ninth Gate, so it doesn't matter.
Copenhagen: Something about this drama just clicks with me.
The Neon Demon: This is the most recent, but somehow it's in the back of my mind almost daily, so I can see myself watching this tons of times.
Eyes Wide Shut: The atmosphere in this is a lot like The Ninth Gate, so I think I'll be watching it often.
There's a lot more candidates, but I'll leave it at that, for now.