Lots of discussion about what might be nice, nothing about what's being shot at, or how far.
Guns are to shoot. Very few people buy hammers to just look at. Yes, some collect tools, like old Stanley planes, but based on the idea they still have to function. If broken, they're junk.
Since the gun has to function, then what is the target? Paper, bunnies, steel plates, remotely controlled, deer or hogs? What distances?
Get what target at what range nailed down in real terms, with numbers, then work out what type of AR suits that best. Few people want a mediocre gun to do the job, it won't help them excel.
So far, most of the links and pics are about M4geries, and what they do best is sell to shooters who don't know what they want to shoot at. They just look cool.
Be more precise, you should choose the appropriate caliber for the target, the barrel length best suited, which then fixes what gas length, not vice versa. That optimizes the best gas, not which gets by. Then optic, furniture, and last trigger. Don't get it backwards, a good barrel, ammo, and optic are most of what it takes to be accurate. A railed fore end or trigger won't make a 2MOA milspec shooter suddenly start grouping .5" at 100 yards. They certainly will add $500 to a $599 gun, but it's not worth $1099. The foundation isn't there.