From 20 yrs. of experience with AR's for long range varmit hunting I think the following.
Almost all AR's are very accurate and function great if you have a good barrel and a good match trigger.
A good friend who has now passed away once stated that the AR receiver is only a necessary item to hold the trigger and the barrel from falling off the rifle.
I have to agree 100% with that statement. We have AR's built out almost every receiver there is and all are sub one inch rifles. But they all have match grade barrels and triggers.
If you build up a AR and it's not accurate it's got a bad barrel and or trigger.
We have never bought a complete AR. We buy good parts from gunshow dealers we know and put them together.
A somewhat secret is that a lot of the AR parts are built by a very few manufactures. And just have various manufactures names put on the item. Mainly true of receivers and uppers.
IMHO.