bottlenose in my opinion. In the few opportunities that I have had to fly the orca i was far from impressed. Its forward gun is very hard to aim and not very powerful. It doesn't have enough armor for its size and it flies like a brick.
Bottlenose on the other hand is a light gunboat to the core. Because it only has four forward firing turrets you need to be decent at firing your turrets in the rear view (v). I've had some success against other gunboats using the razors and pulses set up.
