Well you are off to a decent start. Ventress and Chewie are probably going to be your weak points soon (if not already)
Chewie has a taunt that only covers one turn and his damage is pretty lackluster. That said, he is decent in GW, especially paired with Barris and her normalization heal.
I like Ventress as she brings a stun and some decent damage to the table. She is however, very slow and fairly squishy. (At least at the 5* I have) she holds her own in some GW fights and the tables.
For cantina battles, keep farming JC. He's your only real option until you can farm Kylo shards (53 I think) he will bolster all of your team rosters.
For cantina tokens, you have some choices to make. You can either keep starring Ahsoka or switch:
1. Daka is good to say 5* and will help your DS battles and GW.
2. Poe brings some good enemy debuffs such as expose and weaken special. (iOS users got him free at 3* I think.)
3. Fives has counter attack and speed debuffs as well as assist attack. Sort of like a light side Dooku without the stuns.
4. Boba. Some people swear by him but I don't have him yet so I'm not sure.
For arena I would switch to farming Sid as he fits with a lot of synergies and will do more than Ventress who you can star later should you choose.
For GW keep farming Luminara and then phasma would be my suggestion but there are other options also.
By the time you hit 60 you should have a great starting core team. You'll them seek diversity for GW purposes and filling any LS/DS holes.
