(See:
http://www.arcengames.com/forums/index.php/topic,12781.msg140955.html#msg140955 for reference)
The MRLS and the laser gattlings are easy to use, general purpose ships that fit well into a "fleet ball" (these two are actually my favorite bonus ship types, because of how easy they are to use without sacrificing too much combat ability)
The sniper and the sentinal are awesome if managed properly; not always moving them with the rest of the fleet but instead letting them hang back sometimes is a crucial part of this.
The armor ship is one of the most durable fleet ships both armor rating and cap HP wise, which is nifty. Granted, their low speed makes it hard to take advantage of that.
IIRC, shell ammo is the most common ammo type in the game, so the bulletproof fighter having an immunity to it is actually pretty nifty. Granted, there isn't much distinguishing them from a generic standard fighter clone otherwise.
The infiltrator is useful like the eyebot is, just with a different set of immunities and other stats (especially speed).
Although it doesn't have FF immunity, the minipod can be even better against lots of important stuff not under FF because of their bonuses and the armor rotting, and they do pretty good against FFs themselves too.
Ever since the AI exclusive stuff got good energy costs associated to them, impulse reaction emitters are actually pretty decent now.
The Z mirror is a pretty neat "revenge" unit, though I do feel that it's cap HP has not quite been adjusted considering the damage bonus it receives. The damage bonus it takes also tends to boost it up target priority lists, compounding the issue.
The anti-armor, Spire armor rotter, armor booster, and the Z polarizer I am withholding too much judgement on until the armor rebalance/rework is complete.
Though the Z polarizer, even in its current state, can be very good if you are fighting lots of low cap ships, starships, or other things with high armor.
I can think of one change to make armor booster much, much better without having to wait for a armor rework first is
giving them a minimum to boost tooI will agree that the raider, tachyon microfighter, and the space tank need help though. (though I would also add the raptor to that list)