I've seen a lot of people poo-poo the military starbase. I'm still pretty new to the game, but I've had great success with them on the top difficulty levels.
Here are some tricks I found:
- Assist based modules, the ones that add to the attack of your ships, stack. In other words if you have TWO military starbases that have overlapping areas of effect, and both have the SAME assist modules, your fighters in that overlap area are affected by the assist of both starbases.
- Enemy AI sets the value of your starbases very high. Often if you position them well you can get an opponent to throw all their ships at one. As long as you have enough constructors nearby to repair it back up (using the repair module) you can withstand massive fleet attacks. When built up enough I commonly use one or two constructors to take out a dozen enemy ships)
- Remember that the assist bonuses are PER SHIP. So if you are going to use assist bases, dont even both with bigger hull ships. Instead create the small hull fighters and crank your logistics. The assist bonus from your star-bases affects each ship in your fleet and your overall fleet strength will go through the roof, the bigger it is.
- The tech cost of getting into the 3rd tier of starbase fortification is very well worth it. If you compare it to the cost of logistics, weapons, defense, miniturization, and so on that it requires to get your fleets up to that same level of power, it costs several times more research.
Incidently as I was learning the game I found the power of starbases while doing the campaigns. Those dreadlords are so powerful and they just kept mopping the floor with me. I tried a half-dozen different approaches and they just completely destroyed me. Until I build a starbase.
I rushed the tech-tree into starbase fort III (didnt even research anti-grav) and built one within 5 moves (the speed of the default constructor) of my forward-most planet. I poured all my military spending into constructors and upgraded it using as few as 5 constructors to have like 40,40,40 attack. The dread lords showed up right on schedule, confident that they were going to go through me like poop through a goose. The flew that frigit right into my 40,40,40 starbase and I actually shrieked when the friget exploded and my starbase was still there.
I still didnt win that game, because while all the dreadlords attack vessles were going after my single massively upgraded starbase, all my planets were just pumping out constructors to keep it up. Everything was great until the dreadlords showed up with the transports. Those guys just flew right by my starbase and took over several planets before i could build up.
From there I just kept a small minimally equipped fleet back that would clean up transports while the dreadlords just wrecked all their ships on my starbase.
From there the path to victory was pretty easy.