What's the best power armor that can be repaired without aluminum?

Solution 1:

The best combination that requires no aluminum would be a T-45 torso and T-51 helmet, legs and arms. Then the repair cost would be only 5 steel for each of the arms, legs and head with 7 steel and 1 Circuitry for the torso. The result being 32 steel and 1 Circuitry to repair everything.