I often like to use numbers to asses what units i will use (or not)
here are some equations i made up :P
(these are not the word of godde so they are wrong, they are not models, they just help you understand a unit)
HP/cost = units "healthiness"
HP/sqrt(cost) = units survivability (ie how likely is it to not die on you)
cost vs sqrt(cost): sqrt(cost) is more predictive of the combat potential of units, 5hp/m on a 50m unit is only 250hp, while on a 500m unit it is 2500(giving it much higher survivability) the sqrt(cost) takes this into account, the same is true for most other stats.
dps*range = damage area (how good it is in a straight up battle)
damage*range = skirm potentia (how good is it at shooting at a target once and then running away)
sqrt(damage)*dps*range = alpha strike adjusted damage area (sqrt(damage) allows increased ratings for high alpha units while negating the bonus because such units will also tend to overkill anything they hit by a large value)
(speed/acceleration)*sqrt(turn rate)
approximate maneuverability (sqrt(turn rate) because even a 2 turn rate unit can maneuver, but massive values of turn rate don't have real effects on maneuverability) (deceleration is ignored, it is mostly meaningless in combat currently) (speed/acceleration
time to reach max speed, more relevant than speed*acceleration)
(HP*sqrt(damage)*dps*range)/sqrt(cost) = combat effectiveness for your money
(approximates what unit will do well in battle)
disclaimer : This gives a very rough guide to what is better than what, it is not the word of godde, or even an accurate model of the game. Combat effectiveness DOES NOT have the capacity to predict the outcome of 2 units fighting*. it is also not accurate when comparing units of vastly different classes, you won't get a good comparison if you try to use it with a penetrator and a glaive. (ill add more as other things i considered obvious enough not to mention are brought up)
*if you want to predict the outcome of 2 units fighting the calculation is quite simple:
unit A has more range
A range - B range
B speed - A speed = if negative value A wins
if positive its much more complex, although combat effectiveness is predictive of such scenarios it is not perfect, many other factors such as the nebulous "accuracy", hitbox size, maneuverability, tactics used and other factors make the results variable and hard to model