I think clerks would apply. There was even two endings where one was less open.

Lost in Translation has a lot of seemingly mundane moments.

So many options in Japanese cinema. It's a more common genre there, or so it seems. Nobody Knows comes to mind.

Nomadland comes to mind. Something about the whole movie makes it so facinating.

Been a while since I've watched it but Kids (1995) might qualify as fitting the category (not sure if it'd be a "best" though).

Jeanne Dielman, 23, quai du Commerce, 1080 Bruxelles (1975) is often considered to be a prime example, I think.

Mike Leigh does movies like that. For instance: https://www.imdb.com/title/tt0100024/

Fire Will Come [2019]

Dogs In Space, an Australian film from 1986. Among the cast is Michael.Hutchence, former lead singer of INXS.

It's about a bunch of young people sharing a house in the suburbs of Melbourne. It has no real story, although from memory it culminates in a big house party scene. It's shot in a pretty unique way where the camera just wanders throughout the house and there are constantly things happening. Conversations sort of start and stop abruptly as the camera wanders around so you have to piece together the different snippets to develop an idea of who these different people are. Watching it sometimes feels like you're a silent housemate of these people, just observing their chaotic lives.

Would stranger than fiction count?

Good Morning

It's a cute movie about little boys refusing to speak because their parents won't let them watch the neighbor's TV. Set in a suburban Tokyo neighborhood in post-war Japan.

Recently I loved Perfect Days which is mostly about a guy who just wants to clean toilets while people keep bothering him.

Its super cute and lovely and extremely extremely simple yet a really good watch.

There's a movie with Phillip s. Hoffman and he's just huffing paint the entire time.

Gummo. That movie confuses me still to this day how it got made.

The Castle (1997)

EO. Bits of people's lives in Poland, told through the eyes of a donkey

Corn Island [2014]

Slacker (this is the pure winner, there are no contenders) Twenty Bucks Chicago Cab