You need to decide what variant of AR you want.
"The Chart" is applicable to those looking for a M4 replica... pretty worthless if you want a National Match A2, a varmiter, or a mid-length-gas light-barrelled tubular-handguarded flat top with a two-stage trigger, fixed stock, and no sights. Etc.
Any gun can fail at any time. IMO it is more prudent to rely on a backup sidearm than to put full faith in the durability of single gun due to its rollmark.
Not too many people are using a personally owned AR stateside as a primary personal protection weapon.... they tend to stand out a bit at work or in the grocery store.
Sometimes it seems people fret less over the sidearm they carry with them than the AR they have in the safe at home.
Still nice to have a good AR though. Personally I would make my decision based on a hands-on inspection. I think most of the major manufacturers selling in the $900 range and up make a decent gun... but also put out some horrid workmanship from time to time.
I am more concerned with a properly clocked barrel than I worry about whether an individual bolt was mag partical inspected. In the unlikely event a small part does fail, I will replace it. That is a lot easier than to fix sloppy machining issues.
I probably haven't handled and looked over more than about 100 civilian ARs. I have owned Colt, Bushmaster, Rock River, and CMMG. Of those I have personally handled, my experience has been that the better specimens appeared to have been from RRA, Stag, Les Baer, Double Star, and S&W. The poorer specimens from Bushmaster, Colt, Armalite, CMMG, and Olympic. Olympic seems to have a poor reputation for durability, though I have no first hand experience with that brand.
Personally I have sold all of mine except the Rock Rivers.