advice please on which characters to prioritise.

chewbaca,JC, Ventress,Poe, and Genosian soldier id go for

Ok. Update.
Leader is Lumi 4 star lvl 48
Chewie 4 star lvl 48
JC 3 star lvl 48
Tano 3 star lvl 48
Ventriss 4 star lvl 48

Currently completed GW twice.
And PVP rank around 180-200.

I need to unlock more LS normal and heroic for equipment matts so I was thinking of dropping Ventriss completely and getting eeth koth so I can push the LS chain and he would benefit more from Lumis leadership bonus.

Reason is I find my DS is very poor 1-2 star lvl 48 and can't complete normal lvl 4.
Hence wanting a team that can do LS side, pvp, cantina and GW without gimping myself or wasting training droids on a 5th poor LS character.

Thoughts

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.

Ok

I do have Poe at 3 stars and lvl 47. but i find him very weak and with no self heal, he suffers a lot? does he improve to make him worth while replacing Chewie.

In relation to Sid, for 80 shards to unlock, what star level does he come out as? 4?