First up, I want all of you to know that I'm pretty much against quick scoping. Why? because there is a reason sniper rifles are called 'sniper rifles' and not a 'one-hit-kill-one-man-army-rifle'. They hould be long range rifles and dominate long ranged fighting.
So, my idea is this: reduce the ADS time to about 0.5 seconds, reduce the weapons as the time you are scoped-in gets by, and when a sniper hits you and gets a hitmarker and not kill you in one shot, your movement speed should be reduced, not much, but a sagnificent amount (a decrease of about 10%-15%). And if you do want to quick scope, i have 2 suggestions:
1) Acog snipers should have the ADS time reduced to 0.45 and Iron-sights snipers should have their aim time reduced to 0.40 seconds. And believe me, I want iron-sight snipers. It is the most fun you can have playing CoD, and it is most satisfaying. Just think, if they would bring back the Specialist srtike package, to be able to become the Specialist super sodlier with an iron sight sniper rifle, it sounds ******* amazing.
2) Make a sniper playlist in which snipers are only allowed and maybe the ADS time is reduced for them.
Another thing about sniping, DO NOT make a sniper like the barret 50.cal that can shoot at 1200 RPM. Not only this is not realistic (and I KNOW that CoD isn't suppose to be such a realistic game) but it is so annoying and irreasonable to shoot with a 50.cal sniper rifle that kills you with one shot at 1200 RPM and make it like a shotgun.
P.S, semi-auto WEAK snipers like the SVU-AS from BO2 or the Dragonuv from MW3 can ADS quicker than the heavy 50.cal high-damage snipers, and they should be suited for a bit more medium-long range sniping, but can also fit long range fighting.