For BO4, AA should be reduced rather than increased with SAB. It's very difficult to get into the hitbox if you're not quite there due to the already powerful AA.
I prefer SAB at 0 for faster strafing, which is important for gunfight survival in BO4. CoD has very responsive strafing, unlike say Destiny, and it's probably better to go with crisper movement.
SAB at up to 65 feels ok for movement in BO4, but it is noticeably slower to strafe. Once it exceeds that 65 SAB threshold, Sprint will cancel.