I have owned JP, Larue, and Knights. I still own the Knights.
I owned a JP LRP 07. Wonderful rifle, accurate, balanced well. However I hunt in cold climates, and the metal hand guard got old on the hands after about an hour. I also couldn't get use to the side charger. Not the rifles fault, just not the rifle for my application.
I then bought a larue Predatar and predatobr. Both were very nice, and very accurate. Fit and finish A+. Solid lock up of the recievers, no wiggle. The Predatar was nice to hunt with. However I sold both, and this is why. Both of them were highly over gassed, with much more felt recoil than both the jp and the knights, even with the addition of a surefire brake. Both left case swipe on brass, and the xtraxn chamber could make some softer brass a little interesting to reload. On the predatobr, I was told I would be able to buy barrels in multiple other calibers, yet still the .260 barrel cartridge has yet to be released to the public. 3 years is a little absurd to get one barrel cartridge available.
Now I own a Knights ECC, it is the sweetest shooting 308 I have ever shot. I added a mams, and holy crap is it a pussy cat. Recoil is very, very light. Brass comes out of it like it was shot by a bolt gun. Its not quite as accurate as the larue, however it has a chrome lined barrel, and still shoots under an inch. The polymer grip panels are perfect on my hands in the cool weather. I love this rifle, it is the pride of my collection.
Hope this helps with some added opinions.