General note- Safety Overrides are worth considering on a lot of these but i forgot about it until i was almost done so here's a general reminder rather than me editing everything.
Afflictor/Gremlin/Hyperion-
Pilot only but super good to kit up with some hammers/reapers and fly around at the start of the battle sniping carriers/cruisers/capitals. I sometimes to keep one on hand, start the battle with it deployed, nuke a ship or two, then retreat and swap to something else. The gremlin is ok here while the afflictor is possibly super ship status with anti matter blasters (which are basically like high ammo torpedoes in this setup). The Hyperion is insane at this sort of thing, but often costly overkill, so i'd suggest only using it if you find it fun, as it's hard to find and expensive to maintain.
Lasher/Wolf-
I tend to kit these out with a couple of different builds and then team them up with each other/some destroyers(hammerhead/sunder usually) so i have small mobile kill squads (having 3 escort 1 who then gets an order to hunt down a carrier on the edge or something). These can be more "fire and forget" in that you don't need to pilot them/constantly order them and can usually do work. LMG's/vulcans/mortars for the lasher (assault cannon is often too heavy on the flux when you've already got ammo feeder) and some mixture of tac/PD lasers/ions, and then the heavy blaster/mining laser in the mid slot. In both cases it's almost always a mix of harpoons and sabots as well, and you kind of treat the blob of units as one ship, so while one might work on the flux the others pop the ship when the shields go.
PD escorts-
Cent/Brawler/Omen come to mind for this. Just kit them out with some ok stuff and have them follow your weaker crusiers/carriers around to help make sure they don't eat a reaper. Obviously focus on PD here and the Omen is insane.
Tempest-
Gets its own slot because i feel that it's the "do it all" ship. You want something fun to fly that can punch way above it's weight and isn't as finnicky as the afflictor? Ok. Want to throw this in a pack of wolves/lashers and wreck ships? Ok. Want to just spam these and annihilate everything? Ok. The ship has some great slots and can bring a whole slew of crazy weaponry to the field while its drones do general work. They're always good to have and it's hard to go wrong with them.
Chasers-
Sort of a unique role (and maybe not worth it right now but i hope it changes) but i like to have a least a few frigates that exist solely to hunt down fleeing enemy ships/convoys. They're often kitted out for top speed and usually have some form of ion/disable weaponry + high impact stuff like hammers so they can chase down and kill all those running ships. Again questionable value since i've rarely gotten something insane from this, but it's a role that only frigates fill well.
Mods-
Mods have a MUCH better selection of frigates (one of the biggest area's in imo the base roster is lacking), which isn't to say the vanilla ones are underpowered, but there's a ton of frigates in the various mods out there which pull major weight and are fun to fly. It's been a bit since i've messed with anything as I've been testing vanilla, but if you have any installed it's always worth checking them out.