I found myself on the opposite side of that argument. I thought the grudge and Ju'on were both very creepy, scary films. The scariest films I've seen in years. i could care less about the plot with that movie and more about the scares. Yes its stupid as hell SPOILERS: for them to "save the house" but damned if i couldn't sleep alone that night.
I did like the japanese version slightly better though. It was better acted and not being familiar with any of the actors or actresses gave me a feeling of not knowing what was next.
The japanese version of the ring, rringu, bored me to death. I actually liked the american version better, I think the better special effects added to the tension.
The scariest movie I've seen lately was Ju'on 2. SPOILERS that movie still creeps me out. That was a scary movie. Great directing in it makes it scarier than the first. Theres this one scene where this lady moves into an apartment and she hreres a loud noise coming from the wall. Everyone once in a while they cut a scene to her hearing this noise. At the end we find out what the noise is. To write it doesn't do the justice but when you see it, its creepy as alll get out. There are two more scenes similiar to that are creeped out as well.
The plot of the movie wasn't unique, but the carrying out of it was great.