For me, it's the conquest for vanilla ships. A nice blend of speed and firepower is always a winning combo, but the thing about it that I don't see anyone talking about is the that it's just about as effective flying backwards as forwards, meaning you can engage with the fresher engine armor tiles if your nose(s) have been pushed in already, making the conquest a lot tougher than the stats would suggest.
For modded however, the undisputed king of the void is the quetzalcoatl (and hatchling as well) from Kingdom of Terra. Just the list of features it boasts should make that obvious. Extreme speed, flexible broadside firepower, huge missile capacity, an ammo feeder that works for energy weapons too, multiple emp emitters, segmented body for stacking defenses...
I could go on, but to list all the perks it has would make this post obnoxious to read. If you can work with its slippery flying style, then it's a ship that best experienced rather than told about.
