Second zeta advice?

Brainsym

I run a rex team in the arena, with EP, wedge, biggs, and zylo. (in the top 50)
My first zeta was Kylo, and niw i have enough for another zeta. Who should i choose?
I dont have kenobi yet.
Possible toons im thinking,
For the arena
- r2 - number crunch or combat analysis
- storm trooper han's unique?

For GW and in general
Vader
Or maul

I dont know who to choose... Im confused...
Any advice in what will improve my arena team and who to zeta???
Please

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Moved to Squad & Character Strategy.

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