The Mirror Qin

The short version: If you don't have a mirror universe qin raptor, get one.

Ok, this is going to sound silly, but... This is one of the best dps boats in the klingon arsenal.

Here's the stat page: http://www.stowiki.org/Mirror_Qin_Heavy_Raptor

The fed mirror ships are just costume swaps, they release two versions for the feds in the lockboxes and they're just "mirror images" of their normal universe counterpart. No doubt some big geek at cryptic thought that was hilarious. The klingons though, they only get one mirror ship. So it's not just a costume swap, instead it's an actual variation.

In the case of the qin, vs the normal qin the mirror loses an ensign tac boff slot and instead has an ensign engineering boff. This sounds like a bad thing, after all it's a tac ship, right? But, you're probably going to be using dual cannons and maybe torps. You already have a commander and lt. commander tac boff. Theirs no ensign cannon tac power. So swapping that slot over to engineering gets you a lot more potential survivability and doesn't cost you anything.

In fact, it likely helps you. When I fit out my regular qin, I stuck dual beam on it just so I could use beam overload 1 and make use of that extra tac boff. But, having more dual cannons instead is definitely better.

The best part is: the mirror qin's currently going for about 500k. That's like, two tour runs? Or selling one purple doff. Or maybe 15 contraband. In short, that's cheap for a ship.

But what about compared to other ships?
Fleet Qin: Has the 3 tac boff, so same problem as the regular qin
Somraw retro: Same slot layout but half the crew and less hull and shields. Gets a slightly better turn rate. Costs 200k fleet credits.
Fleet Somraw: Still half the crew, but more hull and only slightly less shields. Also gets an extra sci console slot. But, costs 20k fleet credit plus 4 fleet modules.
Scourge retro: A good chunk less hull, but slightly more shields. Better turn rate, and an extra sci console. Biggest disadvantage is cost, 200k fleet credits. Also, can't cloak.
Fleet scourge: Hulls still less, but at least closer to equal. Shields a fair bit better. Still can't cloak. The extra engineer boff becomes a sci boff, which is better is your call.

I wouldn't pick any of the fleet raptors over the mirror qin. Compared to the scourges, it's more of a toss up. They both have some advantages, but also have way more price.

If you think you might ever need/want a klingon dps ship, you should pick up the mirror qin while they're cheap.