See I'm different. I love subtitles and hate dubs. Korea has the best slow-burn psychological horror movies. Mother/Train To Busan were both Korean. I cover alot of Korean/Japanese/Indonesian/Thai/Filipino horror on my Penthusiast show.
Some of the best Korean psychological horror films are:
I Saw The Devil - Serial Killer
The Chaser - Serial Killer
Memories Of Murder - Serial Killer
Bedeviled - Woman snaps after going through mad abuse and kills everyody
Office - Salaryman snaps after working at the office too long and kills everybody
Monster - Serial Killer
Hansel And Gretel - Dark fantasy tale
I mean there are way too many to mention but alot of them have to do with Serial Killers. And the fact that South Korea doesn't allow firearms means that weapons like knives, hammers, pipes, etc. get used more often leading to some really gory shit.