The only thing I can say is you can not go wrong with anything you buy from Rock River Arms Inc. They are one of the finest rifles out there! And have a limited lifetime guarantee. And that great RRA 2 Stage Trigger they are famous for.
And of course the model you want depends upon your intended purpose.
I doubt you could find a better rifle for tactical hunting. I mostly hear good things about RRA. My one friend thinks his Operator Elite is a little heavy compaired to his S&W AR or my AR. But he still likes it.
they are definitively one of the best around butt the cost is what gets me so i build my own mutts and they work just as well so my personal opinion is to just go get one out of a hock shop lube it up and i bet you'll be just as happy