My 2 cents as well.
AAA: I’ve heard many people suggesting to reduce the cost to 4. Actually an AAA gun is better than infantry already if it can potentially fire at 3 planes.
For calculation purposes:
6 AAA (30 IPC): 18 hits on planes. Averages 3 hits.
10 Inf (30 IPC): 3 1/3 hits.
While the infantry does a little more damage, this damage probably only goes to enemy infantry. Additionally, planes hit by AAA can’t even fire back once.
Now the infantry of course has 4 hp more and can fire in the second round as well, but if the opponents attacks with such a large force that requires 6 AAA, these 10 inf will probably die in the first round anyway. This means you should always defend with as much AAA as necessary.
Now if AAA is so good at defending, why aren’t they never bought? Simply because most powers start with enough already. The capitals start with 3-6 already, this means they can defend against 9-18 planes!!! Just replace some starting AAA with infantry and you will see people will start buying AAA. Of course some powers just don’t need them (USA, Japan for example).
If you allow AAA to shoot at 4 planes, they will be bought even less, since you need even fewer!
Cruiser: This is by far the weakest unit per IPC. It should cost 10 IPC to match a fighter. It’s still weaker in defense, but does not need a carrier and has the bonus of bombardment.
The suggestment of cruiser having AAA ability sounds very interesting too, since cruisers don’t have a special ability at the moment (besides bombardment), while every other ship has.
Battleship: Looking at damage and hp, battleships are slightly weaker than destroyers (clearly weaker in the first round of battle, but stronger after the first round). They can bombard (which isn’t super important, though, since rarely used) but can’t be used as blockers and don’t negate sub first strike. However, if you manage to repair a battleship, that’s worth a lot. Having one battleship in your fleet is very useful to absorb the damage from blockers and other single ships. Since all powers with a fleet already start with at least one Battleship, you almost never see a battleship purchased. Lowering the cost to 19 might already solve that, although 18 might or might not be necessary.
Submarine: Actually the submarine is the strongest sea unit right now. Nothing is even nearly as good at attacking, as the subs.
But what really surprises most: Submarine are the strongest in defense too, if compared with carrier+fighter. Submarines are the cannon fodder at sea. The best possible defense combination at sea is:
5 submarines per each carrier+2fighter.
This trumps every other combination, IPC-wise. Since submarines are ALSO the best attacking unit, your fleet should basically always look like this:
Enough destroyers to have all the blockers you need
Enough destroyer to kill off convoying submarines.
Enough destroyers to support your carriers against an air-only attack (submarines can’t help here).
0-2 Battleships to absorb hits when attacking smaller fleets (if your carriers can’t be damaged)
5 submarines for every full carrier. More submarines, if you’re the aggressive power.
This means submarines at the moment are too strong. A possible solution would be to raise the cost AND damage. Maybe 8 IPC, but 3 on attack (needs to be calculated, haven’t done that yet). This would mean the sub loses its cannon-fodder status and becomes an attack-only unit, similar to bombers.
