Eagles, Drovers, and Hammerheads are nice. With Hypervelocity Drivers and Heavy Maulers.
Personally, though, I think it's more fun to play without buying ships, just salvaging everything (aside from a handful of ships you really want and can't find in salvage). Then you end up with a lot of Pirate Falcons and Enforcers, and Luddic Path Lashers armed with LMGs. Just go to some system that placed a system-wide bounty due to pirates or Luddites and start hauling in the loot. If your fleet is weak you can join battles in progress (particularly with a battlestation).