Just farm Rex and roll a strong Windu fleet. All the DS tl meta ships are not unlocked yet and they do take long time. I would go for Windu, Ahsoka, Biggs, Umbaran, Rex, Plo
and for reinforcement:
JC, Clone Serg.,Phantom, (Ghost when cap ship becomes 7*)
Ps. Chimaera is good but G8 thrawn with 5* Chimaera is not good. plus the ships that are good with it are not unlocked. So I suggest Windu is clearly the way to go. It's not at all bad!
I think @Woodroward 's advice above should be better tuned for your current roster since I know he runs a Republic fleet and maintains the top rank. He is the expert for you.
