I have also specked out missile boats for the 1st war in the early game but since the AI, diplomacy and economic changes have been deployed, I found they were not needed/optimal anymore unless I want to go for harpy tech which I never do as its unfair against the AI who cant use them
Since the above changes went live though there are more options:
In most cases I dont need actual but percieved firepower. Whereas I would have built rocket only light cruisers with no armor before, now I smack on armor and prioratize RF modules to ramp up percieved firepower for better diplomatic bargaining position. In most cases I can skip the inital war phase altogether and have the other factiosn duke it out without draging my faction in their conflict
If the above is not possible I would have hired mercs in past as well but now I rope in as many participants as I can to form an alliance block with.
As for fleet composition I use boarding and cloacking modules where possible
In early game I take what I can salvage from derelict colonies and race affinity the rule is rather what not to use no matter what and those are: Ion weapons of all kind and Interceptors
Early fleet composition derives from necessity rather then early planing for me
In mid game I prefer to have transport ships for boarding action as that is the most resoruce effectvie way to fight bar far in the current balance and a large number of small escorts counting destroyers and light to meadium cruisers with lots of PB + 1-2 heavy hulls with heavy guns for sniping enemy planets (a single heavy ships and heavy gun is enough to snipoe planets without any losses if there is PD around that ship)
In my last war I almost always employ the following strategy with great success even if ouclassed by tech, pop and military power:
1. 3-4 bombing fleet containing 1-2 heavy hulls and a few light escort with mission to bomb everything around my and my allies borders. These fleets are not to engage enemy ships but are simply there to wipe the border regions clean and deal with any light defenses that might be there beyond PD and bases (which are powerless against heavy weapon range)
2. 1-2 Strike fleets to engage pockets of enemy ships where losses are not likely to be high. These fleets consists of the best tech and as many large ships as possible, no destroyers usually. This tactic is for sure an exploit in many regards but it is so damn effective by cutting fleet ranges and denying the enemy resoruces that I simply cannot keep myself from not endulging in it
3. Endless waves of small fleets with 1-4 destroyers and a single light cruiser max. These fleets are tasked with covering everythign else: destroying enemy outposts and preventing new ones, protecting own and allied planets from strangling transports, providing reconnaissance, blockading enemy systems (sometimes even starving the pops) and even dealing with small scale invasion fleets if they have the time to pull together from the near area to put up a fight against them. The ships for these fleets are usually being produced in endless loop around 1-2 production specialised planets
The last fleet type I have introduced since the updates to the strategic AI. Since then the AI has been much better in conducting focused invasions but has also become very vulnerable to a swiling fleet of tiny ships all around the galaxy and hence dies a death from a thousand paper cuts
As for late game I sadly also dont have any sort of experience with heavy dred and dred star as my games never lasted long enough to get to these
My games are typically 100-120 starts with normal spread, normal difficulty, and all enemy factions once (duplicates are not good due to color coding, naming and duplicate insignias). With this setup my games and by turn 300 the latest and mostly at around turn 250
I am hoping we will get another faction or two some day to get enough density within those stars to last a game till late game tech