I actually see a lot of people preferring 360 distance for ADS in this game. Either way, any method should work but they all have their own pros and cons.
360 distance makes running around corners and precisely turning around etc easier.
MDH 0% will make tracking moving targets the same, but it will be a lot slower in terms of 360 distance.
MDH any other % will make flicking to that point on the monitor the same, 100% meaning flicking to the edge.
Viewspeed Horizontal is about the same as MDH 70% and Viewspeed Vertical is about the same as MDV 133%. The difference between these and monitor distance is that they will vary a small amount depending on your input and output FOV (+/- 1-2% or so).