Looking for advice and wisdom. I'm building my first of two or more ARs. I have a Mega Arms Gator lower and a Vltor MUR upper on the way, but I am having problems choosing a barrel. I know the specs I want: 4150 chromoly vanadium, chromed bore and chamber, M4 feed ramp, 16" with mid length gas system, medium contour, and threaded for muzzle devices. I've narrowed my choices between DD, BCM, Armalite, spike, or criterion. Which is the best of these or is their another I've missed that's not going to break my wallet. My 2nd will be the same specs except 18" with rifle length gas or 20".