I like the Thunderbolt VII (a.k.a. the Lead Sled) best. Compared to the Hellcat it has 20% more shields/armor, 40% more power in the forward guns, a tailgun, and a torp, in exchange for 10% lower cruising speed and 10dps slower turning rate. The only really big drawback for me is that its afterburner speed is only 1000kps.
Unless I am going up against lots of Darkets/Strakhas, where I would prefer an Arrow, or against multiple capships of destroyer or heavier class, where I would take a Longbow, the Tbolt is my choice. It has guns heavier than anything but the Excalibur and better shields/armor than anything but the Longbow, yet has more gunpower and maneuverability than the Longbow bomber.