Not to detract from the story-related and gameplay ties to mechanics discussions that emerged naturally from just talking about availability of Lion's Guard ships (showing how good the game is on several aspects)... but at the end a Lion's Guard fleet was probably the most effective and fun fleet that I figured out, planned and realized.
Executors being piloted by Aggressive officers carrying only 6x Ion Pulsers and 2x Autopulse Lasers can kill fast (or make enemies retreat half dead) while being safe with how much shield damage they can tank and how the Ion Pulsers will EMP enemies really fast. Wasn't using Autopulse because I had Reinforced Bulkheads and Insulated Engine Assembly (for campaign and extra safety), but putting them was way better, since the AI uses them effectively. They pester the enemy from the extra distance with Autopulse (and barely increasing flux by controlling fire) and then switch to using the Ion Pulsers at close range (or firing everything if they have enough flux capacity left). Gearing them well for venting makes them extremely aggressive, since they will often force a capital to vent at weapon range (due to the EMP burst and being fast, I think), keep firing, and then start venting at the exact moment that will make them finish venting together with the enemy, exiting vent with reloaded weapons and zero flux. The flagship Executor has built in High Resolution Sensors instead of Resistant Flux Conduits (becoming a normal hullmod), and removes Flux Distributor, but otherwise are the same as the others (having visual range makes the AI behave so much better).
Sunders being flown by Cautious officers carrying only a High Intensity Laser and two Graviton Beams can destroy or pressure away any small/fast ship (and larger when in groups), and if geared for highest range and being ordered to defend the Executors will stay under them while being a thorn to anything nearby. If maximized for flux dissipation, they will fire all beams all the time at any target, and since they are already fast, they will retreat under the Executors really well (and the Executors are going to finish anyone silly enough to follow). Sometimes one will be taken down, since the AI does tend to let them get nudged out, but more often than not any battle finishes without a single one even taking hull damage. Also, you need to stagger their launch to only after the Executors reach near the range of station battles, otherwise Sunders rush too fast if they were dropped together with them.
It's a fleet that I can go against a 350k bounty fleet, command each Executor to Defend, Seek and Destroy (hit D and S), and do nothing else, ending the battle with no loses. Not only that, it has the lowest Supply consumption overall including repairs and not needing to slow down against hyperspace storms because of damage thanks to s-mod Solar Shielding (without losing one of the other 3 slots), a hullmod that's still critical for the fleet (Executors become more tanky, and Sunders are able to survive riskier engagements). It's a fleet that I can send from bounty target to bounty target without stopping to repair or buy supplies (I'll run out of fuel before supplies, from 7k fuel and 3k supplies). Oh, and it's a 238 combat point fleet, just 2 points under the soft cap for most related skills, with 11 ships (no ships without officers). Tight.
...and being able to fly around like this made me question: why does the Diktat cower inside the Core worlds, and only in one system? They have the largest fuel production of the Core, allowing them to travel around anywhere, and they also have the ships most capable of traveling the system fast and safely (no pirate is going to run full speed into a storm). And yet, they satisfy themselves staying on a single system inside the Core. I get being a totalitarian regime they don't want to spread themselves a lot to keep unity. Still, they are the most capable faction to be able to set colonies outside the Core AND function well, while also being the least likely to. Such a disparage between capability and reality. Now I have a newfound appreciation from them, even if it comes from being salty over ship availability and baffling unrealized potential.