Brawler is hard to justify because it has no defenses whatsoever. It cannot defend against Salamanders, and once one of them connects, it becomes hopelessly crippled before the enemy finishes it off.
Cerberus and Hound are practically haulers that can be made to run from nearly anything. With Makeshift Shields, they can be disposable attackers much like Enforcer, Mule, and Shrike (P). If they die (and not used for hauling), who cares? Past early-game, they are obsolete like nearly every other frigate.
Gremlin is the civilian phase ship. I would bring it if I need to sneak-and-raid Sindria/Culann for blueprints, but I do not have other phase ships available (unlikely since New Maxios has all of the phase ship blueprints, and New Maxios is practically undefended). As for combat, it is probably like the others not named Doom - good only as a glorified bomber, which only the player can use effectively.
Hermes/Mercury are from a bygone era when fleet size was determined by Logistics instead of a fleet cap.
Hyperion is not very useful today now that 1) enemy fires at phased ships (which includes teleportation) and 2) huge multi-capital fights where lack of peak performance hurts Hyperion very badly. Today, I much rather use four Reaper Afflictor if I need an elite frigate to kill something big fast. Endgame fights in 0.9 are much bigger than endgame fights of pre-0.8.
Lasher is decent as a frigate. The problem is nearly every frigate becomes obsolete past early game.
Scarab would be easier to use if it had 360 front shields instead of 180 omni shields.
Wayfarer is almost obsolete as a combatant as soon as the game begins. With Apogee start, it is usually the first to die every time, and I keep it only because of its capacity, but it gets dumped as soon as I can. It is vulnerable to attacks from behind.
The only frigates I care to use as combatants early are Centurion and Wolf. Late in the game, the only frigates I care about are Tempest and Afflictor. Tempest for being fast and powerful, and Afflictor for doing Reaper cheese Harbinger used to do.
Wolf has barely enough OP with Loadout Design 3. It needs better flux stats.
Even though Condor is inferior to Drover, it still gets the job done. Condor is good enough to use until player can find better carriers.
Enforcers have the advantage of being ubiquitous, and they (along with Mules and Shrike (P)) form the backbone of my early game AI fleet until they get phased out by better ships later in the game. They are decent bricks with decent firepower. They are probably not as good as Hammerhead, and are a bit sluggish to pilot, but they work well enough earlier in the game.
Gemini is OP starved. It is not one of those ships I want to use if I have other alternatives. With Reserve Deployment significantly weakened in 0.9.x, it is not that good of a carrier anymore.
Medusa either should get more OP, better flux stats, or have its cost dropped to 10 or 11... or Light Needler range restored to 800. It needs rare weapons (like railguns) to do anything useful, and even then, it is maybe slightly above par. By the time I can obtain Medusa, it has become obsolete, and I need cruisers to fight.
Shrike is seriously OP starved, especially the superior pirate version. I cannot fit a basic loadout without Loadout Design 3. Even with LD3, something gets cut. Shrike (P) is about as common as Enforcers, and they do a decent job bullying small ships. Normal Shrike, by the time I can access those, they are obsolete. As for Shrike, it probably should get the hybrid used by Shrike (P), and Shrike (P) could either have reduced OP or have the hybrid downgraded to energy. As for in the game, Shrike (P) is about as common as Enforcers, and they too get used frequently early in the game, only to be replaced later.
Gryphon is simply too fragile. I rarely use it if I loot one early and turn it into a Hammer suicide bomber, sort of like a extra large Enforcer. The main reason I would like to use Gryphon is it is the only ship aside from Legion (XIV) and maybe Prometheus 2 that can easily aim dumb-fire large missiles like Hammers and fire them at the enemy.
Aurora needs its 0.8 flux stats back.
Astral is great. I consider it the #2 most powerful ship in the game, behind Paragon.
Atlas 2 is really slow and awkward to use. Very sub-optimal to use. Good only if it is the first capital you find and you are desperate for capital-grade firepower.
Prometheus 2 feels a bit like a Blackrock capital, only much slower and without the teleporter Karkinos has. It is still sub-par compared to other capitals, but it is not too terrible, and its DP cost of 32 seems about right.
My biggest gripe with Onslaught is the TPCs and heavy mounts do not overlap well. If I want to outfit it for AI use, I need to focus on the TPCs, because the AI does not tilt the ship to focus fire two heavy weapons at enemies (except maybe Hellbores occasionally). As for Annihilator Pods, they run out far too quickly in 0.9's endgame fights against ten enemy capitals and more. I find myself gravitating toward Typhoon Reapers, Salamanders, or even Swarmers with Expanded Missile Racks. Another big gripe is I need to put Augmented Engines on it (while I may not need to on Conquest), and with that much OP gone, it has an OP budget comparable to Conquest. Overall, I do not mind Onslaught, and it is useful enough.
Odyssey is an annoying ship. AI likes to burn drive into mobs while its lack of defenses make it vulnerable to damage easily. Also, it is a bit OP starved. Would like to see stronger shield (or more armor), better flux capacity, or more OP. At the very least, more idiot-proof to use by AI. Currently, Odyssey is only useful as a playership because only the player is smart enough to not burn into a mob and try to tank everything thrown at it by the enemy like the AI does.
I think a lot of carriers are in a tough place OP wise. None of them feel like they can fit high end fighters without totally sacrificing everything else on the ship. I have to leave weapon mounts empty throw away all hull mods except the carrier ones and cut almost all vents/caps to fit the best fighters. I think most of the dedicated carriers could use some extra OP, just to make the good fighters usable without gutting the loadout. Maybe that's by design but losing OP is not the direction I would go with carriers, I don't want to have to get built in hull mods on every carrier want to use nice fighters on. Carriers feel like they are balanced around ~8 OP fighters.
I would also add the doom as a ship where I never have anywhere near enough OP to put the things I want on. It could use an extra ~10-15 imo. But it's system is also super strong so it's in a weird place. I would nerf the system a bit and give it some extra OP, but that's just me.
I am not fond of carriers because they generally need to sacrifice almost everything to use fighters bigger than Talons, but despite that, they can wreck enemies. For Astral, I use six bombers, and it only has five heavy burst lasers, and it still wrecks ships fast. However, it is not satisfying when carriers must be practically unarmed to use fighters effectively. In the old days, it was fun watching Heron brawl like a Wolf or Tempest while fighters did stuff, and kill ships. Today, Heron needs to stay in the backline and let fighters do the work.
Doom does not really need much for weapons. All it really needs are two Heavy Blasters and maybe burst PD, and between that and mines, it can do serious damage. That said, either I need to give up Hardened Subsystems or four mortars and some vents. Doom with LD3 is not too OP starved like some other ships, but I would not mind more OP, especially now that LD3 will be gone.