As swift stated, it depends on the roleplay you are seeking.
I don't know much about the Outcasts because I haven't played them. But I do know that the Corsairs operate alot in the Omicrons and Omegas which leaves room for alot of pirating freedom.
It all depends what you want:
Area of Operation:
Outcasts you have allot bigger Zone of Interest. Operating in more core areas as well as the Border Worlds such as Taus, Liberty and the lot.
Corsairs a bit smaller. Mainly operating in Border Worlds (Sigmas, Omegas, Omicrons) and Bretonia.
Ships:
OC have somewhat faster ships.
Corsairs have more slower ships but they are tanks.
Examples: Sabre vs. Titan and Outcast Gunship vs. Corsair Gunboat.
And a whole lot more. What do you want to RP more and you think will be most enjoyable?
Bomber, works better versus transports and if a rival Pirate group comes at you. You have a better chance at surviving.
But some fighters such as the Werewolf and Gladiator. They have both a CD and a CD/T slot. Mount screamer mined, Mini and CD and some guns and your ready to rock.