From Ghibli (and therefore of any animated films) I'd say objectively Totoro, as personal favorite Porco Rosso.
Mononoke is the third candidate for that, being the most action packed and because of that most rewatchable.

Tarantino(/Rodriguez?) does have a place in this discussion. If you count Kill Bill as one movie - the two parts balance each other, making it better than either alone - it's the best Tarantino film. If not, my favorite is Jackie Brown. Peak Rodriguez are the Mariachi trilogy, I suppose the big budget last one best of those.

My singular favorite movie is Your Name. It is a gorgeous, fairly unique movie, that has a great story. I sometimes worry that I won't like it as much, but every time I come back to it, the story hits. 

Greatest film ever made:

I feel like I'm cheating if I said Lord of the Rings, since it's 3 movies. But I think those movies are an absurd achievement. The battles are huge, the soundtrack is one of the best ever. The first movie literally has a scene where it's a guy looking at a ring before dropping it, and the movie succeeds in making this feel like an epic moment. 

There are lots of movies that I enjoy, but LOTR is the only one where I feel ready to sit down for ~11 hours and enjoy basically the whole thing.  

Lots of other good mentions like The Godfather, Shawshank Redemption. 

12 Angry Men, I would also throw out as an incredible movie. Watching 12 men talk in a single room for 90 minutes has never been so good to watch. And the part that gets me, is that you don't even know their names. 

I am actually quite pleasantly surprised by the choices here, given the demographics I expected movies from the last two or three decades, but instead many of the choices are older than me. Which means both I and others here didn't watch these movies when they were current but much later, which is kinda a trait of a cinephile, not only following current trends.

Anyways, of the ones names I second quite a few. Vertigo is also for me the best Hitchcock, although I think Rear Window or North by Northwest are easier to digest as an entry point to Hitchcock. Kurosawa was named, I think Seven Samurais is great, but I would give the edge to Ran, classical Shakespeare (it's King Lear). Modern Times is a great movie by Chaplin, probably the best of him, The great Dictator being close second. Shoutout to Stalker, one weird ass movie that always plays with the idea of the supernatural, but it never is. Yes, the movie is connected to the game series Stalker, both are based on the novel Roadside Picnic, which differs a lot from the movie and is a good read. Casablanca is an absolutely great movie which has some of the best one-liner:

• I think this is the beginning of a beautiful friendship.
• Round up the Usual Suspects!

The second one is inspiration for the title of the movie the Usual suspects, which is also one of the greatest movies and I think wasn't mentioned so far:

https://www.youtube.com/watch?v=x3t0Nc6fg7w

Dr. Strangelove was mentioned in passing, I want to highlight it more, IMHO one of the best dark comedies ever and the best Kubrick film (which might be controversial given his movies are all great and some are more well-known):

https://www.youtube.com/watch?v=0rF5XftjRGM

Ghibli was mentioned, but not the in my opinion best Ghibli movie (which is not a Miyazaki movie) - Grave of the Fireflies:

https://www.youtube.com/watch?v=lhlh7JVcTt8

(just watching the trailer let's me tear up again)

And the best Hayao Miyazaki movie (which is not technically a Ghibli movie) - Nausicaä:

https://www.youtube.com/watch?v=l46khRlReRc

I see a lot of these are war-themed. Maybe go to lighter themes, I think Tarantino is a great more modern director, and the best work is IMHO Pulp Fiction:

https://www.youtube.com/watch?v=s7EdQ4FqbhY

Maybe I should stop for now, let's just do one more. Highly experimental iranian movie. I was a third in when I realized that the movie is (except the beginning and the end) is shot in one long 90 minute take. The camera is following one guy that plays himself in a police reenactement of him killing another person (which is considered self-defense but the police still wants to get the details straight), but beside the reenactment we see also other things happening now and possibly what really happened. Also they have three rounds of reenactement and the roles are switching somehow. Very abstract and metaphorical. And the last thing I expected of an Iranian movie were themes of homosexuality. I watched it at a festival, the crew was there, the cameraman talked about how the take was planned out in detail, even how long he would stand still and which of these were long enough for him to take a sip of water. Not the easiest movie to watch, but probably the weirdest movie you can find. Hojoom:

https://www.youtube.com/watch?v=TmDtY_Bllak

There seems to be the full movie on Youtube too, which will otherwise probably be hard to find, so you can search for it.

12 Angry Men
Amadeus
Christmas Vacation
Ed Wood
Evil Dead 2
Fallen
Falling Down
Fargo
Groundhog Day
Jaws
JFK
Jurassic Park
One Flew Over The Cuckoos Nest
Papillon
Planes, Trains And Automobiles
Se7en
Swiss Army Man
Taken
The Godfather
The Hateful Eight
The Shawshank Redemption
The Thing
The Usual Suspects
Zodiac

Just some of my favorites.

City of God is right up there for me to.

From its creative editing and cinematography to its brilliant writing and acting it's an incredible portrayal of life on the edge.

Whoa! A Brazilian movie being mentioned!! I enjoyed City of God a lot, but even for Rio de Janeiro it's a bit over the top (as in, the favelas are not all the time a gang war zone, and most are peaceful places), but very good nonetheless. I guess, from my side, as a Brazilian, I was still under shock after Central Station a few years early (really, it is THAT good, and the comparison made me feel a bit like "yeah, City of God is very good, but I prefer the other one kind of thing - makes no sense, I know lol, but it is an effect anyhow) and mainly because, few months before City of God released, an even better movie came out that, to me, is more effective in showing life on the edge as you say. It is "O Invasor" (O Invasor - Wikipedia). Check it out, if you haven't. It's not as action oriented and "hollywoodian" as CoG, but man is it good. 

The new one is also very good.

We will soon rewatch both as a Double Feature in my home cinema... in German of couse:

Löhne umsteigen!

I often think movies (and also games) are things that exist on the intersection of art, entertainment and product. They are not a product like cars or refrigerators, but still you can make money and optimize for market and that gives money for bigger budgets. But art while often bad for profit is important to push the boundaries of the medium and explore ideas. Entertainment is best if it meets an equilibrium somewhere between.

I just got reminded of this, and I think it fits this thread, because that is there one of the greatest movies is created. But first, let's look at an art movie, that is highly interesting, innovative (it's from the 60s) and experimental, but also hard to watch and because of difficult viewing experience maybe not one of the greatest movies. Actually, maybe movie is even wrong, as maker Chris Marker calls it photo-roman (photo-novel) — I talk about La Jetee:

https://www.youtube.com/watch?v=WstrUci5Fbg

By the way, Chris Marker was strongly drawn to Hitchcock and a movie named here in the thread: Vertigo. La Jetee carries elements of this movie. Anyways, while I would say it is a hard watch and more an artistic exercise, this was the direct inspiration for one of the greatest movies, changing more into the equilibrium, being entertainment: 12 Monkeys by Terry Gilliams. I think this is a beautiful reminder how art and entertainment never exist in a vacuum, they build on each other, inspire and enrich our culture.

https://www.youtube.com/watch?v=4tT8lpQz3N8