Composite doesn't need a counter. It's weakness is its cost, smart commanders hardly research composite because of this very weakness. With other armor types, you get 2-3 times as many tanks compared to composite. That's the advantage of other armors, cheaper and good enough protection.
It does not have to be composite, I only added it to get peoples attention, Mwahahahahahahaha It might just be a good overall weapon, except a weakness to Absorbent
Absorbant isn't the worst. Good starting armor to research and fairly light. Doesn't have enough resistance against railguns and ranged cannon compared to how well reactive is good resisting Bio and Missiles/rockets/explosives.
Since wages, resources have been fucked up. You won't be able to go composite every round in the next version if I can fix that shit.