Honestly, whatever makes more sense to you and whatever your shooting buddies use. To me, I grew up learning and talking MOA and inches. I judge everything in inches. So for me, to see an impact be 3" low at 600 yards, it's easy to convert that in MOA and call out 1/2 MOA low immediately when I'm spotting. If you were trained/taught to speak MILs when shooting, then you'll understand the value of MILs. I don't get caught up in it to much. Whatever is easier to you is the way to