I have deceided to built a new upper instead of just rebarreling my upper. So the question becomes which of these 3 uppers is the best one in regauds be true dimensionally and not put any stress/binding/torque on the BCG. I am concernd about the mechanical aspect not the looks of the upper reciever

I have heard good things about the Stealth uppers being vey good, but I don't know much about the other 2 brands other then what I have read at their websites about tolerances.