I wouldn`t say that it was the scariest, but it was definitely the "most aggressive" Silent Hill. It`s focus wasn`t melancholy or depression but hellish suffering, pain and anger. It was more about consistent terror unlike the other games of the series.
I know what you mean, and that is what I found to be most frightening about it. It was like being trapped in some kind of existential nightmare from which there is no escape.