Slitherine

I have a question about enemy unit moving into VH with my two or more units attached to VH. AI is somehow forced to attack but which one of my units. The strongest, the one most on the right or random?

AI is normally looking for most vulnerable and most expensive target, i.e. to get more bang for the buck.
if you are talking about the ambush, when AI doesnt see the target and cant decide, i believe that would be dependent on a path pattern, which is in 5 of 6 cases is "first forward then turn right", and only 1 of 6 "forward then left"