the current trend for the ar-15 seems to be for close up CQC types of scopes like the ACOG or 1-4x 24mm big game scopes.
the current trend is to try to extend the 1-4x types out to 6x or more the few cheaper types of 1-6x i have looked through seemed to lose a lot of light at 6x, the more expensive ones do much better but even then they can't really compete with a 2-7x 32with equal glass.
sure you can make the 1-6x or more work but they get expensive pretty quick, that $$ could be spent better elsewhere i figure ( for survival prep)
PA is coming out with a 1-6x 24mm like their excellent 1-4x for about $250, is is supposed to have low end japan glass like a nikon pro-staff or better. it could be great but it could have a very tight eye box as many of the 1-4x are sort of tight --the extra mag might make it even more critical. so i'll have to wait and see on um myself.
many like the tweener types of scopes like 2-7x32s and such as a economical solution .
the 1-4x types of big game scopes and the 2-7x32 and so on do have a weight problem --most of the 2-7x types weigh in at about 13 oz and most of the 1-4x 24mm scopes weigh in at about 16 oz or one lb--
so neither of them are saving much if any weight over a 3-9x40 or even a 3-9x50mm.
taking a few measurements on some of burris one piece mounts -- it looks like a 50mm scope would clear nicely.
now i know that some people use 50mm scopes for night time coyote hunting and hog hunting with no artificial light.
now SWFA has some minox 2-9X50 scope with the #4 post for $199 in their samples list.
i'm just thinking --wonder how that big glass would do come dark? would it be useful IF you scrounging around at night in a SHTF type of world?