FDL is shield tank, Gunship is hulltank, and Python fits inbetween. Up to you how you like taking hits.
In terms of damage, they are all pretty similar, except the Gunship is probably in first.
Maneuverbility wise, the ships your looking at are bricks, if you don't like that then your out of luck, FDL beats them both. However, the FAS and Clipper are more maneuvarabke than the FDL, so if that's your main concern look into them.
However, the main selling point of a Gunship is its fighter bay. If you don't use it, might as well have the Python. But that fighter bay can and will come in handy at times, so think about it wisely.
I think that's everything. Good luck in your choice, but always choose fun over function, trust me, I've been there.