Transports

[Doom]

well each transpprt has its own style of defending...

Bumblebee from the first post has 5 backward firing turrets, along with good strafing and small fwd profile u simply can fly straight, use strafe and fire all 5 turrets to back....
GMG miner has 6 360 angle turrets and if turrets are used in link fire can down any bomber.
Mammoth and Percheron both are agile enough to turn in time and use all of its 5 turrets on any attacker.

Pirate transport in next mod update has 8 fwd firing turrets, and with new transport turrets you have numerous combination's of defending or attacking.

Listed above are mid sized transports, and of all transports they have very good ability and chance of defending themselves.
Anything larger then 4000 cargo is simply too slow to face bomber or GB. But they make money faster...

I personally fly GMG miner and i never lost a fight against lone pirate in bomber or fighter...GBs are different, but one can escape them with some luck...

So choose, defensive capability and agility while trading, or sitting ducks and tons of credits....