I just recently played a game vs the AI on a medium 4 player map. With victory set to homeworld. I researched some civilian research to get refineries and boost minining output and on the military side, starbases and max fleet supply. Before I began my assault, I had a starbase at each of my planets which only numbered 6. And all planets had defenses maxxed. I had 6 CAPs defending an my ice planet, plus full garrison. Pirates, and enemy attacks on the world were all unsuccessful and they were mostly just going for that one planet.
I literally mopped the floor with 100 light frigates, 100 corvettes, 10 siege frigates and 15 flak frigates. I did have an Akkan, and Sova Carrier, but the outcome wouldnt have changed if I did not have those. And I did not have any components installed on them. I did not encounter any enemy starbases, Did have an engagment with one of their fleets but they were wiped out fairly quickly as they were out numbered. I barely lost any ships on my assault. Any enemy CAPs were gunned down in seconds if I targetted all my ships on them.
The AI probably isnt fleshed out, and against a human player I would probably have hit more resistance, or have the same tactic used on me. The AI tried to swarm my planets but they just didnt send enough to counter when my fleet arrived. They did kill a base level star base and some plantary defenses but they got mopped up quickly with my Akkan, Sova, 50 light frigates and 50 corvettes. They attacked with a CAP or two and had about 40 light frigates and possibly some missile or torpedo cruisers.
I feel ship types need to be more tactical. Frigates/Corvettes should barely scratch a Capital ship. And to take down the CAPs efficiently, bring missile and heavy cruisers to the fight. And reduce the shield and hit points on frigates. Corvettes seem fine as they are easily killed, but I barely lost any during my assualts.
Or give ships resistance to other ship types, or use the armor penetration as a value on how effective a ship type is against others. So lets say a ship at a base armor level 10 and the armor pentration of the attacking ship was armor penetration 1, then treat that as the attacking ships weapons are only 10% effective. If you want to treat the numbers that way. Planetary defenses should be able to pop frigates faily quickly. I never encountered more than a few turrets and/or hangar defense on my attacks so the ones I did encounter went down fast. Fighters/Bombers could also have stronger attributes vs Frigates as well.
Another thought, is to give the Scout ship weapons, and move the light frigate to Military II research tree. It would slow expansion a bit, and provide a linear progression to more advanced ships, limit the frigate swarms early on, although, it would just prolong being able to do what I did. Corvettes pop fairly easily as I lost 50 of them when I attacked a starbase during another game.
My goal in this game that I just played, was to build my defenses first (as I had orbitaing planets enabled) Then build my frigate/corvette swarm to see how fast I could wipe out the AI players. I think there needs to be a counter to swarms like what I pulled off. Starbases would have limited how quickly I could do it as I would have to rebuild ships lost as they kill corvettes pretty quickly. I also did not encounter any garrison forces.
This is just my feedback, as most of the military research was not needed unless it enchanced my corvettes and frigates. And I only needed 6 planets to take care of business. They were sending pirates at me every chance they got, but my defenses were enough to hold them off.
Could move the ship types further down the research tree as well. Just move them all to the right by one, along with my scout ship suggestion and making the light frigate a research option. This would make the scout, and corvette more useful. As I would only make enough scouts to uncover the map, and most the time would never bother with the corvette. It is kind of pricey in early game, and the light frigate is more economical and lasts longer in a fight.