kind of depends on what u plan to do with it, be a lil more specific, me personally for what i do, i chose to top my rra midlegth ar15 with a konus 6-24x44 scope, i like to target shoot in the off season so i like a larger scope to get out and see things with u know and it works great for coyote and fox hunting in the winter, so for my use i dont really want a red dot aiming device ie aimpoint, eotech, pro point , you get the drift, i like to have some magnification and i dont do any real tactical shooting so they just dont strike me as a good deal for my ar, although if i wanted to spend 900$ + on optics i would consider a trijicon ACOG i really like them but not practical. so i guess what you need to find out is what u plan to do with you are there are many option to go with u just need to find what suits u best like i said all this is just from my point of view so take it for what its worth i hope this helps you.
adam