stealth_nsk
Deity
Either the attacker would get to choose which unit to target or the most defensible unit would take the damage, with exceptions. ( example melee can target rams ) Rams would have a bonus to taking hits from archers basically requiring melee units to kill them. Anti tank guns would have a bonus to tanks obviously so on attack or defend get a bonus, with armor you probably aren't going to target the anti tank gun but with a ranged unit or bomber you would attempt to destroy it first.
It looks quite complex and it's not that 1UPT. Anyway, we have to wait and see. The actual implementation could depend on a lot of factors.