All Godzilla movies…:-)
Seriously, when it comes to horror, these films are quite interesting to see.
Besides these monster movies there are also many Manga movies like Akira that are interesting to see.Although this is a cartoon, it is one with an enormous amount of violence in it. What at Manga is actually the standard.
What you see especially in Japan is that they have a huge history of horror stories that were mostly first translated to comic strips and the popular stories were eventually filmed as comics, although some (low-budget) films have become.Outside the Manga industry, Japan does not have a major film industry if you compare it with the US or Europe. This is partly because the Japanese population has been much less concerned with this kind of entertainment and because after WWII there is a huge influx of western (American) films.
The Grudge as expected?
Or Itchi the killer.
How scary are you looking for?
The original Japanese films of The Grudge (and there are about 8 of them) are all pretty scary.
Chakushin Ari, the Japanese original of the horror film One Missed Call, is quite good and also pretty scary.
Kayako vs Sadako… was not so very scary.
Horror films work by using ideas that are creepy, and those ideas slowly but surely make bigger in our heads.In fact, dancing are all not scary because they are fake, the only reason we find them scary is because they are very real in our head while we are watching.
All variants of The Grudge (Ju-on in Japanese) The ring (Ringu in Japanese-also about as scary as the American remake!) and also Chakushin Ari, make good use of this.Kayako vs. Sadako does this badly (for reasons that take a long time to explain) and is… Nice, to see, but not really scary.
Apart from all this… Pretty much all Japanese horror is good.
Japanese horror film producers often make masterly use of music, much better than most other langen.Especially in Chakushin Ari this is well forward.
What most countries do in their horror films, is to use music to put the atmosphere.This can work well in creating tension, but because of the music you always have the subconscious feeling that it is fake-the reality has no music.
That’s why Japanese horror film producers often do scenes without music at the times they want us to feel as much as possible about the situation on the screen.
For example: You see images of a city, a setting sun, a dark forest… All examples of scenes, creating emotion and generating feelings.So: Music.
Then you see the main character walking through an abandoned hospital, and… Silence.Sometimes a few minutes long. You almost forget that you are watching a movie, and if you finally hit the monster or the spirit of this film, you are afraid to be totally more frightened.
Therefore, I can personally say, that virtually all Japanese horror is advisable: it is a different style of frightening.You can look for yourself if this style suits you better, or less well than the western style.
Hope this answer helps!