Go with Ackbar as fleet commander. Don't buy the starter packs, but buy the slave1 + boba combo that will show up for you soon. Best ship I have IMO. I finish Rank 1 daily. Pick (4) Dark side ships and (4) Light side ships to get to 5 stars, and one other dark side to 4*. I was able to beat the tarkin challenge and the zeta challenge with a 5* tarkin G7 - Level 53, and his ship at level 50.
I would suggest:
Light Side:
Jedi Consular, Biggs, Fives, and Wedge or Ashoka
(Rex's ship is great, but it's a long farm, I'd rather finish off the zeta lineup before farming it)
Dark Side:
Boba's Slave1, Sun Fac, Genosian Soldier, and either the First Order Tie, or the TFP
(Vadar's ship is great, but also will be a very long farm that could hold you back)
I also bought Kylo's command shuttle and love it in combination with Boba, but I can't farm it currently, so it's stuck at 4*. Up to you if you want that.