I actually agree with Waratah, there are very few BSs in the game that are actually bad (the only two that I can think of are the Liberty Carrier and Sarissa, which are both far too big for their stats and just massive targets). Some BSs just take a little more tactical awareness and planning to fly successfully, the Zephyr being one of them.
Zephyrs can take on Ranseurs and win if used right, they can also get utterly slaughtered by Ranseurs if used wrong, the difference is just a matter of pilot skill.
Oh and half a dozen Ranseurs will get absolutely annihilated by a group of several Bombers, as the Corsairs have proved so many times, so if a bunch of Pythos (which are much smaller and more agile than Praetorians) can't kill those Ranseurs, then they must be doing it wrong.