I believe that ranged horse units have the most bang per buck, more than any of the formulas seen on this thread. After all, HA can empty their quivers before charging, causing morale penalties and huge casualties, thus their overall damage potential is greatly increased.

Does anybody have any ideas how to factor in the missile attack? On another note, could this be utilized in creating a more balanced unit training for the AI? I have no idea how the AI prioritizes its unit training.