My design is a combat triangle of Melee > Sub > Ranged > Melee, gradually transformed from the Melee = Ranged parity that's Corvette and Frigate, and Ironclad and Cruiser.
By making ranged ships have high CS, low RCS but a +50% against melee ships, they counter melee ships, do okay against land units, and have an extreme weakness to submarines. They also don't have resistance to planes, but won't fall that easily. Armor Plating on Missile Cruiser would stop it from taking much damage from pretty much everything except submarines, which is definitely not balanced.
Melee ships' role changes from tanking and taking cities to intercepting planes and protecting ranged ships and carriers from submarines towards the lategame. VP made them too strong, so I lowered their CS a bit.
Submarines are supposed to be weak to melee, but withdrawing from melee counteracts that, so it has to go. High RCS makes them resist ranged ship attacks.
(Super)carriers' high CS makes them resist air strikes. Low RCS hopefully reduces the AI's tendency of using them to attack directly, and makes them weaker to submarines.
Of course, all changes were just theorycrafted and I still have to test them using the current AI game.