Afk

You need to decide what you want to focus on - Arena, Raids, Events, TB, TW.

If you haven't got Thrawn, personally I'd suggest him as he's a good basis for both Empire and Sith squads but is also viable in Arena with most toons. His Capital Ship is the best imo. Plus getting him requires strong Phoenix squad which is useful for TW.

After that, looking back on the benefit they add, I'd probably suggest Bounty Hunters - Will allow you to unlock Chewie and the scoundral/smuggler events. Plus, some good ships in there too.

I don't have NS or Ewoks hgeared and I've been playing three years (regret not doing Ewoks now of course).

I'm sure others will have different opinions, it's really down to what you want to focus on first.

Thanks

After a one year hiatus, it will take a loooong time for you to become competitive again in squad arena. It's doable, but you will have to have the foresight and jump on the right META train, when the option arrives.
However reaching rank 100 is definately possible (but still takes months to reach). Your best bet would probably be to farm Bastilla to 4* and build a jedi team with her leading. In the mean time, make sure to be in an active guild, which raids often. You will need that gear and currency to develop your roster.

For GA, there are several viable team compositions available. Each can act as a counter to another type of team, you face on offence.

But yes, I would definately go for CLS, Thrawn, EP and GMY legendary/hero characters for GA. After you have those, you can chose between several options: Collect bountyhunters for Chewie (BH make a good team themselves), collect FO and veterans/Rey Scav/Finn for JTR (A loooong farm before you finaly reach the goal), or maybe ewok for C3PO (No idea if he's worth anything).