Fantastic Planet stands out, as do the Flรฅklypa movies. Once Upon a Time... is nostalgic for me. Birdboy was a doozy I watched a few months ago, I can certainly recommend that one.
There were a lot of good animations from the USSR, but the one nearest to my heart has to be Polygon. The USSR didn't produce many animated series but there is Vesyolaya Karusel' and Nu Pogodi and stuff.
The DPRK is best known for Squirrel & Hedgehog. Otherwise, anilist.co actually lets you search for animation from Mainland China, Taiwan, and South Korea. I've personally seen Look, I Can See Your Ears! which I think was actually a Chinese-Japanese co-production, and I saw the film Nezha recently.
I guess I can also mention, like, '90s Tintin and Aardman stuff but like, everybody knows those already.
The UK generally has a lot of good stop motion, though. You might already know Bumper Films' Fireman Sam, but did you know Bumper Films also made a show called Joshua Jones? It's cute, it's fun, it's positive Romani representation in nineteen-ninety-friggin-two, it's a neat little historical artifact.