Rules of Thumb for Statmaking
Kill Ships cost more Metal
Emp Ships cost more Crystal
Steal Ships cost more Enoium
Cloak Ships have same cost
Terran - slower int, high A/C, low D/C kill ships.
Cat - quickest int, medium A/C, no D/C for emp ships.
Xan - quick int, low A/C, high D/C.
Zik - slowest int, medium A/C, medium D/C.
Etd - depends on which ships you use! As a rule though i personally have never made an Etd ship better than its counterparts, ie. Etd Stealers wouldnt int before its Zik rival.
Emp efficency is something that really affects the race distribution in stats. There have been trends but we are starting to find a balance around 145-155% T1 efficency. That doesnt mean you cant go higher or lower just be aware that doing so makes emp ships Gods or Runts!!!
Cloak is a very powerful ability. You may love Xan and cloak like your own child but its power is very delicate. You need to make sure you dont have too strong a ship with cloak or you will have 100% Xan round, and no one wants that!!!!
People forget that Resource Stealers are still a thing in this game! You can make these ships part of your stats if you want. They steal a certain amount of resources during combat depending on what the target has stashed away.
Structure Killers dont need to be nerfed to hell. The game already makes them hard to use so giving the 100 A/C and D/C doesnt do anything useful. They are capped to 10% of total structures and Structure Defence can reduce that to 0%. Plus you can only use them in War Mode.