Moin 8x is the maximum I use . I mean, I don't care if people want to increase their tunnel vision even more, go ahead.
At what range are you sniping? 12X gets the job done for me, but I rarely use anything higher than a 7X..... (front line sniper if you cant tell).
At 12x with a high velocity rifle you never have to compensate more than a mil-dot at infantry render distance anyway. If infantry rendered at a longer distance then maybe it'd be justified, but until then you'd just be handicapping yourself getting a 16x scope.
16x and even 20x would be good options to have for render-range sniping. I probably wouldn't use either a whole lot, but more options are always nice.