Help Me Decide What to Farm

I am finishing up work on my Empire squad for the next R2-D2 event, mod battles, and other things you need one for. After I finish that, should I farm the characters needed for the CLS event (I already have ST Han, but that is it) or should I farm Resistance characters (I am halfway done with Rey and I have Resistance Pilot halfway farmed)? I already have a Sith squad and a Rebel Squad. Thanks!