Accelerated Shields: Excellent for player-piloted larger ships, more so with omni shields. Worthy for AI omni shielded capitals too.
Additional Berthing: Obvious pick for crew transports.
Advanced Optics: TL Sunder or Paragon.
Advanced Turret Gyros: As long as ship has enough turreted weapons with medium to low rotation speed, this is likely to be useful.
Augmented Drive Field: When you have few ships larger than the rest of fleet.
Automated Repair Unit: I see how it can be useful to reckless SO brawlers, but don't use builds like that.
Auxiliary Fuel Tanks: Obvious pick for tankers.
Auxiliary Thrusters: Can be useful, but somewhat overpriced for what it does.
Blast Doors: Had to check exact effect on wiki. So yeah, I don't use it, crew is cheap enough.
Converted Hangar: It's powerful for Buffalo mk2 or Valkyrie spam, but you can't do that in campaign. Good for Enforcers too. Too OP-inefficient for cruisers or capitals.
Dedicated Targeting Core: If I don't have ITU.
ECCM Package: For missile builds.
ECM Package: I see how it could be useful, but EW1 is usually enough without it.
Efficiency Overhaul: So cheap that I'm sometimes tempted to use it even on direct combat ships, especially considering faster CR recovery.
Expanded Cargo Holds: Obvious pick for cargo ships.
Expanded Deck Crew: Carrier ITU, as others said.
Expanded Magazines: If you have 2 or more Autopulses.
Expanded Missile Racks: For missile builds.
Extended Shields: Mine protection for ships that don't have slots for proper PD. Otherwise they tend to take lots of unnecessary losses against stations.
Flux Coil Adjunct: For phase ships.
Flux Distributor: Any ship that can fit it without compromising build.
Hardened Shields: I might use this even more than ITU (because frigate ITU is crap).
Hardened Subsystems: "Its more like tax for the small ships."
Heavy Armor: It is somewhat useful on an Onslaught and less so on similar low-tech ships. Problem is, AI doesn't use armor aggressively to win flux wars anyway.
High Resolutions Sensors: Only if I get it for free with the hull.
Insulated Engine Assembly: Occasionally used to compensate D-mods.
Integrated Point Defense AI: IR Pulse + IPDAI combo.
Integrated Targeting Unit: Every CR/Capital, most DEs, crap on frigates.
Makeshift Shield Generator: Net negative. Ship with this wastes flux that could to weapons on crappy shield and has less speed (a lot more than you'd think, due to less efficient use of zero flux boost). Only useful to counter non-massed Tac lasers (massed would crush inefficient shield anyway).
Militarized Subsystems: Any civilian ship that would drop fleet speed or raise sensor signature otherwise.
Nav Relay: On combat-size 500, reaching 20% is not a problem without it. I guess it could be useful for small battle size.
Operations Center: Don't like the playstyle.
Recovery Shuttles: Crew is cheap.
Reinforced Bulkheads: When I have nothing better to put on an officer-less ship.
Resistant Flux Conduits: Core for player ships. Much less useful for AI.
Safety Override: Strong, but I rarely use it in campaign.
Shield Conversion Front: Stabilized, Accelerated and Expanded all in 1. Still, losing omni and OP-cost make fairly niche.
Shield Conversion Omni: Too expensive considering the downsides and that front-shielded ships tend to be built around hardpoints anyway.
Solar Shielding: As far as I remember it doesn't affect shield damage in current release. Will become a must in next one with shield damage reduction.
Stabilized Shields: Some ships like Paragon have too high maintenance otherwise. Also can be used in combination with other hullmods to max out soft flux resistance.
Surveying Equipment: "It does exactly that it says."
Unstable Injector: Auto-pick for most frigates. Also DEs If don't have access to ITU yet. Very niche on larger ships.