Unless you are adding some ships with mods, I think the Paragon is pretty clearly the best ship in the game, even considering it has a 60 point deployment cost. They are blisteringly fast for their size (3-4x as fast as the comparable Hegemony battleship, for example), 4 Large slots that can all be fired forward (firing arcs really can’t be underestimated in this game), the highest ordnance capacity in the game, a built in and free +100% range targeting computer, a 360 shield arc, good flux-shield efficiency, and excellent built in flux dissipation.
But I’m pretty firmly planted in the belief that there isn’t any point to running ships smaller than Battleship sized once you have access to/can afford them and their upkeep. The way that flux capacity works means that smaller ships are simply overwhelmed immediately by larger ships that concentrate fire.
Something like 2 Paragons/3 Astrals properly kitted should be able to defeat anything the vanilla game will throw at you.
Edited to add: You could field 10 low cost frigates instead of a Paragon, but good luck ever getting those 10 frigates into firing range of the Paragon without being volleyed down one at a time long before they enter their own relatively pitiful weapons range. Even if you could, you’d be replacing incidental losses constantly, which is just a chore you don’t need to create for yourself in this game.