In the long run, you'll want to diversify your fleet squad to have dark side ships. If they add more content around ships you'll be lacking if you completely ignore one side of the equation. Depending on how poorly you've neglected dark side ships, you may want to first accelerate your farming of dark side ships through the fleet shipment. You can supplement by getting Sun Fac, Tie Fighter, Geo Soldier all from GW tokens. Also always get Slave 1 and Scimitar from the fleet shipments as those are 100% worth farming in the long run. Then whatever you have leftover buy Zetas.