Add Core 15 to your list. Haven’t been able to shoot it yet, but it won’t accept some pmags while accepting others.
I’m pretty confident in pmag manufacturing quality.
Yes, I have heard some bad things about their quality control.
Some other brands I forgot to mention in the mid tier:
Windham Rifles are trending upwards
Bushmaster is trending downwards
I personally own two S&W ARs. I am happy with them. I got them with $100 Veteran’s rebate, a good buy for the value. S&W has the best customer service in the business. Colt’s customer service is terrible, but you usually don’t have any problems with a Colt AR.