Barriss and Ahsoka would definitely be my top choice for things to play since I don't know many Ahsoka muns. I'm fine with playing from any timeline, since Barriss's fate was never clear she may have survived the purge. Trying to find some common ground after Barriss's character assassination would make for a fun setup I think.

As for Luke, I play Luke from around ROTJ and from Legends. Legends Luke is radically different from E7/8 Luke, since he never gave up on training Jedi. Either could be interesting!