Re: AR-15 use stock sight,or red dot???
I would say it depends on what the rifle is used for.
Quick acquisition is typically better with a dot.
If ya got time, I'd say iron sights are better.
My 16" HBAR has a dot on it as well as the std carry handle sights.
My 20" HBAR is scoped w/YHM BUIS.
The carbine can carry/use both at once.
The 20" can use one or the other at a time.
They have their own purpose, and are equipped as such.