I use Missile Frigs as my baseline most of the time, which on normal/normal mk I is a little shy of 100k, as my generic anti-whatever ship. If I'm not beating that, I'm most likely going to ignore that ship except as fleet filler. So, I'd say in the 125-150k range for being non-triangle. Bombers are actually pretty low on the DPS scale but that huge boost to FFs and Heavy's is really what you care about with 'em, as well as fortress killers.
Here's an example: If you're going to have an artillery damage multiplier, don't do it for AoE ships. The primary one of those we care about is the missile frigate. In this case, the artillery multiplier is probably useless. Now, AoE multipliers for Swarmer or Close combat, on the otherhand, would be HUGE... because you would be laying waste to the hundreds of the little buggers that are coming up on you. For single-shotters... who cares? It's useless.
Sometimes it really comes down to that too. The only thing in ultra-lights that are dangerous are the leech and raid starship. Leech really isn't all that dangerous by itself, it's just a damage soak. Raid is deadly, but that's because of speed+ff ignore. If you catch it, it melts to normal fleet, don't need the bonus.
So, by Class:
Artillery: Nearly pointless multiplier on anything that doesn't have LONG range and doesn't AoE (I'm looking at you, Lightning Turret).
Close-Combat: Again, not really caring about these, except in cases of Blade Spawns. Nothing else in teh list of Close Combat ships is so heavy duty I need specialized boosts against them.
Command-Grade: Oh for the love of god do we need boosts on these. I think bombers are literally the only ship with this boost, but I might be wrong. If for nothing else than killing wormhole guardposts.
Composite: Beam Frigate and Gravity Drain/Rippers are in this category. Dangerous ships with heavy impact on your fleet. Needs to have range 8k to matter, to beat out the Grav Drain, 10k by preference to beat out the Beam Frigate.
Heavy: What ISN'T Heavy? Beachheads, Gatlings, most Guardposts (in particular spire shields), most of the SpireCrafts (particularly the dangerous ones).
Light: Pah, there's nothing in the light list that requires bonuses. Almost all of them die, one at a time, if you sneeze on them. Maybe if it was AoE.
Medium: Blade Spawners need to die, as do a few guardians (Zombie). The Sentenel frigate and teleporters also exhibit this armor type, but no teleporter hits hard enough for me to worry about a ff falling, and Sentinels don't usually have the #s to need a significant boost against them. Meh, nice to have, but I wouldn't go out of my way for it.
Neutron: Electric Bomber, EMP Guardians, Impulse Emitters, Mirrors... There's a lot in neutron that's dangerous, IF the AI pulls these up. Most times you won't even care. A missile firing neutron guy? Sounds great. A shortranged one with no armor and slow? Not really. EMP Guardians you're almost always hunting down with Raid Starships anyway.
Polycrystal: Bombers, Tigers, StarBombs, Tanks. Two of those are always in the AI's arsenel. Poly bonus = goood.
Refractive: A non snipe, non missile refractive multiplier would be nice in a turret. As a ship? Not really. There's nothing in refractive that gives me pause except Raptors, and they shatter if you sneeze on them (meaning you caught them). The Vampire Guardian is also in this list, but they're just annoying to kill, not highly dangerous.
Scout: AI Carriers.... your milage may vary here.
Structural: This probably doesn't need to be expounded on. Structural = FFs. FFs = Player survival and permanent problems for players on offense. Anything else is just gravy.
Swarmer: Pah, it all dies when you sneeze on it. Silly little bonus.
Turret: Utterly unimportant to me, as AI craft if it doesn't have long range or gravity ignore it still probably isn't a signficant concern.
Ultra-Heavy: Every golem ever, so important if you're playing a golem exo game. Otherwise, Maws and SSBs can be a serious threat if the AI gets them. Otherwise, meh.
Ultra-Light: Really only if it has wicked high speed or long range, otherwise there's nothing in Ultra-Light that doesn't die to your standard fleet pretty easily.
These are pretty accurate. It is not just the multiplier, but also how the ship stacks and reacts to target ship.
Artillary: Speed or range is a must on the attacker. If the attacker does not, the bonus feels wasted. AoE on artillary feels very wasted.
Close combat: Seems to "same-y" to swarmer or ultra-light. I tend to mix them up. These tend to be tougher, but since all the swarmers and ultra-light ships come in swarms and have lower then average range you want multiple shot close range weapons.
Composite: These highlight the need for missile frigates. They force a need for long range firepower and the frigates deliver.
Command-grade: All niche things: Command stations, hunter killers, etc. But since these big things are filled by bombers, too, you don't get confused.
Heavy: With most starships having this, it is needed in every game. Thankfully, this comes generally with ultra-heavy, so these two "heavy" threats (pardon the wordplay) are covered in the same counters.
Light: Fighters and their ilk can devaste fleet battles since they are tough with decent dps ; being generally moderate in all regards, they don't seem threatening, but not to be discount except against heavy defenses.
Medium: Nothing comes to mind to make me think: "I'm glad I got a bonus against this!"
Neutron: These mentally are the "odd balls". Mixed bag.
Polycrystal: Everyone fears bombers. Always good.
Refractive: Well, these get fried by lightning turrets. So on defense, who cares, since they don't have long range. On offense? They don't seem to hit hard enough for their health.
Scout: Niche.
Structure: Everyone needs structure. Always good.
Swarmer: Boom. Gone. Oh, there were more? Good things bullets are free.
Turret: Does this ever matter, since the ai does not use it in either usage or targetting?
Ultra-heavy: Always feared, due to golems
Ultra-light: All these units need high speed and range to be of any use, since they are flamsy and not in huge numbers.