AF is more a preference rather than requirement. You can look at it like you look at a camera depth of field and aperture (sort of). The higher the value the less blurred texture at a distance. You need vsync on with gsync for less tearing around the edges of the screen. It works differently in combination with gsync and only applies frame time compensation to reduce (eliminate) tearing at edges. What you don't want is to reach the max Hz/framerate where vsync kicks in full introducing more input lag etc. Also gsync in windowed mode cause stuttering and problems with software like photoshop etc so rather keep it for full screen only.