I confess I can't seem to design a competitive fighter using carronades, lasers, particle beams, or railguns at any tech level. Meson and microwave fighters, however, might be worth more of my attention.
Just one of the issues that fighters face include the requirement for decent-sized FCs to get acceptable accuracy at any but point-blank range. Carronade fighters don't have this issue so much, but they
a) require that you have superior Reaction (to move last and so choose their range in the sub-pulse), which means you need to devote chosen leaders, leaders that could instead be commanding bigger, more powerful ships, and
b) the small carronades that fighters can carry lack both armor penetration and shock damage capability.
And think of the play value here: Is there any point to a small carronade? The whole POINT of a carronade is to ram a bigger gun muzzle up in somebody's face and light him up, space pirate-style.
Speaking more holistically, Aurora has a number of game rules and interfaces that favor large - or in some cases medium-sized - ships, including how FCs work, how weapons other than missiles, mesons, and microwaves work, limited number of well-qualified commanders, how armor damage and (especially) shields work, the tedium of organizing and then commanding large number of ships in battle, and the outsized expense of fielding warcraft with meaningful dodge capability.
I, therefore, actually never build fighters. Missile fighters make it too easy to beat the AI (or, at least, make sure its fleets and orbital defences never get a chance to inflict return damage). Meson and microwave fighters want more of my attention, but I'm a knifefighter kinda guy, and I want my carronades, lasers, particle beams, and/or railguns to get a fair chance to win. And that requires hull sizes at and above ~1kton. Right now, I'm running a pack of fast carronade-armed, armored 2.5kton gunboats around, operating off of carriers. They're not particularly cost-effective, but they give the AI a chance to shoot back ... and make bad guys go boom in a heart-warming way.