Been reading through old balance discussion threads (1, 2, 3, 4) but because those threads are up to 8 years old I'll have the audacity to make a new one instead of responding to one of those.
This thread will be about (Citizen Soldier) units that deal Hack and / or Pierce damage, and how they can be given distinguished roles with just Hack Damage, Pierce Damage, Hack Resistance, Pierce Resistance and a Damage Multiplier against Cavalry.
The values presented are not set in stone but to illustrate the core principles.
So lets start with the core triangle:
Infantry Spearman:
75% Hack, 25% Pierce
Bonus Damage against Cavalry
Infantry Archer:
100% Pierce
Long Range
Cavalry Swordsman:
100% Hack
High DPS (due to high RoF)
-1 Hack Resistance (from Cavalry Melee)
+1 Pierce Resistance (from Cavalry Swordsman)
Faster than Cavalry Spearman
These three units form the most distinct Rock Paper Scissors triangle. Cavalry Swordsmen's high speed, high damage and high Pierce Resistance makes them decimate Archers. Infantry Spearmen decimate Cavalry Swordmen thanks to mostly their bonus damage, and Infantry Archers weed out most Spearmen before they can reach them.
The next three units still uphold the triangle but in a (sometimes far) less pronounced way:
Infantry Swordsman:
100% Hack
High DPS (due to high RoF)
+1 Hack Resistance (from Infantry Swordsman)
Faster than Infantry_Spearman
Infantry Javelineer:
25% Hack, 75% Pierce
Low Range
High DPS (due to high damage)
Faster than Infantry Archer
Cavalry Spearman:
75% Hack, 25% Pierce
Small Bonus Damage against Cavalry (1.2-1.5)
-1 Hack Resistance (from Cavalry Melee)
Compared to Cavalry Swordsmen: Cavalry Spearmen still beat ranged infantry, but lower DPS, speed and Pierce Resistance makes them less effective. They are slightly better against cavalry despite lower DPS thanks to their Bonus Damage. They perform about equally good against Infantry Swordmen thanks to part of their damage bypassing the +1 Hack Resistance of them.
Compared to Infantry Archers: Infantry Javelineers are better against Cavalry due to them partially dealing Hack damage. Their lower range does not make that much of a difference against cavalry as cavalry can close the distance quickly. They are weaker against infantry due to having to be far closer, and having partially Hack damage does not offer them any advantage; in fact, against Infantry Swordsmen it becomes a disadvantage.
Compared to Infantry Spearmen: Infantry Swordmen lose to melee Cavalry due to their better stats, but cavalry's weakness to Hack damage and their own Hack Resistance means they barely win cost-for-cost. They win against Spearmen due to their own higher DPS and Hack Resistance. They are better against ranged units due their higher DPS and speed.
Infantry Pikeman:
25% Hack, 75% Pierce
Long Range, High Damage, but low RoF (DPS slightly below Infantry Spearman)
Bonus Damage against Cavalry
Slower than Infantry Spearman
Compared to Infantry Spearmen: 1-vs-1 Infantry Pikemen are the worst melee infantry unit. They become much stronger in numbers as their long range and alpha strike damage allows them to kill some of the approaching melee units before they can fight back, snowballing the fight in their favor.
Not sure about Cavalry Archers and Cavalry Javelineers, so I'll put them in a spoiler:
edit:
Here is the mod to try out these ideas: