Aimpoints - Comp vs Comp ML - which one?

[bk40]

I own a Aimpoint Comp XD dot sight and I use it on my Ruger MKII pistol. Now I want to put another Aimpoint on my Bushmaster AR rifle. The intended purpose of this rifle is informal target shooting and varmint hunting at ranges less than 200yds.
1. Which model Aimpoint would you buy & why?
2. What size dot do you prefer & why?

Thanks!
.......... bk40