Mmmm if you compare them to themselves, my opinion is that the originals are better then it gets worse as it goes on.
Ju-on the curse was ok. Ju-on r the curse 2 was better. Ju-on the grudge was amazing, ju-on the grudge 2 was maybe a little confusing but I thought was really good (compared, you'll see why in a second) then the American ones were ok, 1 ok, 2 meh, 3 oof, and the 2020 one was refreshing but meh. Then there was black ghost white ghost the beginning of the end and final chapter all of which I felt lost the plot completely. And they're was a sadako vs kayako cross over but I haven't watched it because I was like "should I do the thing movies to🤔🤔🤔"
Overall though. Compared to other films but just it's own timeline, I think they're ALL just meh. Out of 10 I think the one I rated highest was a 7🤷🏽. I guess I just don't find em all that compelling. But they do have done really cool shots and poetic reasonings behind things which is cool.