Honestly buying one of everything seems the way to go. That gives you one of all the ships at leads, but generally 2 or 3 in some cases. Having eventually 3 T70s, or 3 T65's, or a regular Ywing and a Scum one to do double duty, is well worth it.
Also it gives you the right number of cards it seems. Imperial Aces and a Awing gives you three PTL. Just about what you want. Same with a bunch of other cards. Extra Munitions, Turret weapons, All of them.
After that you can specialize. Need that extra Awing for a 4th PTL? Need that extra Jump Master?
Yeah, but it would also mean buying a lot of ugly garbage like E Wings, Punishers, K Wings or Phantoms.