I would defenitely take a 16" mid length as my first or only AR15. The 16" mid length gas system is the sweet spot in the AR. The difference is really not that much between a 18" and 16" I don't think it is enough of a velocity gain to warrant the extra weight and length. Also remember that an 18" is not more accurate than a 16" the only thing it offers is a little more velocity, in fact a shorter barrel (all else being equal) is typically more accurate than a longer one as they are stiffer.

BCM 18" SPR & DD 16" Recce


After having both the 18" SPR type and the 16" Recce type I understand why the SF types preferred that 16" Recce it just seems to handle better and can make hits to the limit of the optic and the shooters ability.

Cameron