Still gotta recommend Burning. It's my favorite film from 2018, and one of my favorites of the decade. Slow burning (sorry), but completely enthralling. It also tackles class issues in a much different way than Parasite, but the parallels between the two in terms of similarity are kinda there. It's not as fun as Parasite is, but both deal with some aspects of South Korean culture, both involve main characters of different class standings, and both shift genres leading to satisfying and unexpected endings.
I have also seen Oldboy but never got around to the others in that series. I remember being kinda obsessed with it in high school though. Never saw the American remake, and I don't think I'm missing anything there. Oh, how much you wanna bet though that Parasite winds up getting an American remake at some point?