I saw Alien 1 just a couple of weeks ago for the first time and I was amazed how good it still looked. The design of the spaceship and the alien itself still looked amazing in 4k on an OLED TV. And also the story still seemed like a fresh idea. Of course there are moments with stupid acting people, but all in all the decisions made felt plausible and logical, not the normal stupid horror movie group. And also the story twist came (for me) as a real surprise and not like a thing you knew after the first 5min. (And I'm also surprised that after all these years it's still a surprise, cause everybody knows the alien but not the story of the first movie?)

Every day, Idiocracy is getting further from absurd comedy and closer to documentary.

The Matrix Still looks great and works as a trans allegory

Gattaca Getting more prescient with each year

Idiocracy

The Thing is a god-damn perfect horror movie, and it hasn't aged a day.

Nearly everything Terry Gilliam made has aged very well for me. He creates strange and interesting visual worlds that never really seem dated because they all sort of exist in their own time-space.

Also anything Jim Henson company touches seems to become immortal. Dark Crystal and Labyrinth are masterpieces.

And to a lesser degree Don Coscarelli has made some pretty timeless films. Beastmaster is still very watchable.

Jurassic Park. Those dinos beat many of today’s CGI films. Mixed in with the animatronic ones they just blend in so well. The story is simple (to quote Dr Malcolm) God creates dinosaurs. God destroys dinosaurs. God creates man. Man destroys God. Man creates dinosaurs. There are so many quotable lines, as shown just now, and the music is pretty unforgettable too.

Demolition Man, they even predicted exactly how covid would work and when.

12 angry men is like a Life Pro Trick sitting unused since 1957

The mummy

2001: A Space Odyssey still holds up pretty well both technically and narratively.

The original Blade Runner(1982)

That sparse and bleak mood will never age. Poses excellent dilemas and moral questions about cyborgs too.

Also Citizen Kane. I watched it a couple of years ago because of it's position in film history. Yes, it is that good of a masterpiece.

Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb

Eternal Sunshine of the Spotless Mind

They Live is pretty awesome.

The Back to the Future films

The Goonies

My vote goes to trading places, because it had both aged incredibly well (a tale of class solidarity against evil eugenics-peddling billionaires), and incredibly poorly (a story about nondiscrimination with that damn train scene right in the middle).

I'd also like yo mention RoboCop and American Psycho because their satirization of American hyper capitalism has only gotten more accurate. It really is depressing that we have the exact same social issues that we did in the 80s.

Bunny Lake Is Missing (1965) — hard to say anything without spoiling the plot

Blair Witch Project (1999) — I just admire how great idea / concept extended beyond the movie itself. No-one can ever watch it again for a first time during ‘99 but it is iconic and great as a case study of having almost no budget and making something really impactful / special

Her (2013) — this one is my answer for the same question but asked in 2061..

The Wicker Man (1974) is better every year and every viewing. That island gave him every chance to mind his own business.

Sneakers

Maybe more relevant today than it was then.

Cosmo was right.

The movie It's a Wonderful Life still holds up pretty well.

Willow. It's beautiful, fun, scary. It's full of flawed people being good to each other.

It's really quotable and has a handful of interesting twists.

Willow has a few great performances. Val Kilmer knocks it out of the park, and Billy Barty is wonderful as the "High Aldwin".

Just re-watched Jumanji 1995 and I thought it held up mighty fine! Some of the CGI is lighted a bit flat, the monkeys specifically (and they get some real screen time too so you can judge extra harshly and at your leisure, but all of the perfomances are at least good and most are great or exceptional. I Also love the plot idea and it's executed really well.

@FatTony

Citizen Kane is still a wonderful film with well-drawn characters, great cinematography, and a relevant message: If you have a hole in your psyche, wealth alone won't fill it.

The Sixth Sense is a fantastic movie. None of the stuff Shamalan came up with after are really worth it, but this first movie is wonderful.

I saw Being There about 10 years ago, and it was made 35 years before that. It is a masterwork.

Network

Ben-Hur

Office Space

Fellow lemmings, for me, it's "Barbie", a movie that aged beautifully over the last uh, 8 months, and its message is as relevant today as it was when it was released July 21st of 2023.

Dark City

I watched the kill bills last week again after not having watched them since they originally came out. It still feels fresh, both in dialogue and action, score cinematography great. Incredible that some lost the brilliance in Tarantino's penchant for a bit too much blood in a few scenes. It would be like not appreciating the Sistine chapel because there are nude angels depicted.

Just watched Mulholland Dr. Years ahead of MeToo.

Whatever Happened to Baby Jane (1962). Timeless in is commentary on both child actors and being a damn good movie. Everything about the makeup makes the absolute most of the restricted grayscale palette. Definitely recommend it if you're looking for a good thriller somewhat akin to Misery.

Slap Shot. Crumbling hockey team, crumbling lives, a crumbling town, a crumbling American steel town, in the crumbling American Dream.

One not mentioned yet that instantly popped into my mind is "Chinatown" (1974), which seems to retain all its' power and intricate excellence as time goes by.

From 1959, Godard's "A Bout De Soufflé" still has the power to amaze, to disorient in a playful way. It manages to still feel fresh, even in black and white.

I watched Cop Land (1997) for the first time a couple of months ago and thought it was pretty good and rather timely. Corrupt, racist, domestic abusing police who refuse to live in the community they work is a theme that never really gets old. I think it would likely been seen as too 'on the nose' if it came out now.

I'm going to tweak the OP a little bit to drop my movie unpopular opinion that I haven't gotten to share here and say:

Indiana Jones and the Kingdom of the Crystal Skull is a damn fine, and more importantly, fun, addition the the franchise that deserves maybe a tenth of the hate it gets online. It's pulpy, it's cheesy, the writing swings between passable and unbelievable, and the plot is all of the place, both in tone and in narrative, but you know what: SO ARE ALL THE INDIANA JONES MOVIES!

I honestly think that if that vine swinging scene never left the editing bay that movie would be looked back on a lot better.