On the note of Retribution, since it's getting mentioned, I forgot about it but I completely agree. It feels like an objectively worse version of the Odyssey. Doesn't have the range to enjoy the benefits of ballistic weapons, nor the armor to be able to rely on PD, so you're stuck with a close-range brawler that has no particularly durable barrier between it and whatever's trying to hurt it and doesn't have the flux to hang out and unload weapons into the target.
Don't get me wrong, it can be effective and even decisive with very skilled piloting, but I can't think of any situation where you'd pick it over an Aurora or an Odyssey. Odyssey broadside is mentioned, but, with the forward-only ship system, it's much, much better to have a broadside than forward-firing weapons. Moreover, the Luddic Church loves to use them in its fleets, but it has no idea how to fight with them, and just gets them killed in the first few seconds of an engagement.
As for special modifications, I know there's pages of discourse on it, but it really should just be non-removable, with Executor stats buffed so that it evens out, and/or it should not be present on player-manufactured Executors. Having a capital ship that costs a full new capital's worth of credits to get to baseline performance just discourages players from using that specific ship, which is rather a shame.
As a side bonus, it'd make the "pristine Executor for massive rep hit plus PK" deal a lot more interesting, since it would be a unique ship akin to the special XIV warships.