There's also a terrible John Leguizamo movie called The Pest, that I'm genuinely amazed didn't end his career right there. The wife was suprised I hadn't seen it, and as we started she just went "you're going to hate it".
Interesting that Point Break (1991) and The Matrix (1999) book ended the decade. Point Break focuses on white 20 something kids that dropped out and started surfing, the The Matrix focuses on a 30ish white guy going through an existential crisis. At the beginning of the 90s there was still some hope, that a person could find a small counter-culture and create if not a wealthy life, of something satisfying. By 1999 all hope was gone.
Home Alone. It's a movie that really couldn't take place today due to cell phones and the Internet making easier to communicate with someone if the landlines are down. Also, the family wouldn't have been able to get through the airport like they did back then thanks to 9/11.
I'll toss in Empire Records - the store set, the costumes, the music, the actors, the meandering listlessness... all scream "this is a 90's movie about the 90's". Plus the whole Rex Manning plot is absolutely what happened to so many 70's and 80's artists. Not perfect by any means, but a great encapsulation of the decade.
It's a 90s movie about the internet, but it's all technobabble magic and represented in a very made-for-TV way. Just the right balance of interesting plot and complete cringe which is pretty much how I remember the 90s.
For not-the-best-90s-movie-but-most-strongly-dated-to-the-90s I'd have to go with You've Got Mail
If someone had told me Independence Day was early 2000s (pre 9/11) I wouldn't have doubted it. Same with the Matrix really.
But You've Got Mail seems rooted to that mid to late 90s early internet feel. Two massive stars. Lots of 90s fashion etc
Possibly also Mrs Doubtfire. Reasons there being very 90s exploration of divorce, prosthetics that weren't available in the 80s and a theme (man sneaking into kids lives in disguise) that I don't think would have gotten traction 2000s onwards for being too creepy. Makes it a very 90s film.
Falling Down (1993), Freeway (1996) are two that I saw fairly recently and the 90's were jumping off the screen.
Pauly Shore had 90's career. Encino Man (1992), Jury Duty (1995), Bio-Dome (1996). His only movie of the 2000's was Pauly Shore is Dead (2003) which was about no one caring about him anymore.
I know a few other people have already said it, but I'll agree: Hackers, 100%. Late DOS/early-GUI computers + skate punk aesthetic? Can't get more '90s than that!
The first Mission Impossible movie is a fun time capsule in many ways. It has some fun stuff with early 90s depictions of computers, hacking, the internet and email, back before anyone knew what any of that actually looked like.
But it's also a great example of the 90s naivete that the US had about conflict and global politics. There's an entire monologue about how intelligence agencies are obsolete because the cold war is over. There was this vague notion in the 90s that world peace had broken out and things were just going to get better and better. And Hollywood sometimes struggled to come up with villains now that they no longer had soviets for that, so you don't see it reflected as much in films, especially since optimism doesn't make for good popcorn flicks, but Mission Impossible captures the thinking if not the warm and fuzzy feeling.
My other suggestion would be Contact. My theory has always been that 2001 A Space Odyssey, Contact, and Interstellar are really the same movie made in different times. As the 90s incarnation, Contact has no international conflict, only internal politics. It's got that I'm spiritual but not religious" vibe that was everywhere in the 90s. It has a vague message about hope, and belief and trying to understand the universe and what's out there in order to understand ourselves... it's hard to put it all in words, it's just the whole tone and vibe of the thing, it's all just so sincere and idealistic.
(For a great big dose of 90s optimism and hope for the future, I highly recommend watching the Adventures of Brisco Country JR. I'd have nominated that, but it isn't a movie)
John Frankenheimer’s Ronin (1998) but not in the way you maybe mean. This movie simply has to take place when it does in the 90s. The plot just wouldn’t work otherwise.
As for movies from the 90's, Jurassic Park would be my pick, with Forrest Gump a close second, but points docked for not being based wholey in the 90's.