I guess Dokuu is the best lead atm.
QGJ is only good for speed as leader - he will have an assist (as long as you didn't stun that slot before), but too low on health. So you might have to make a decision between Dooku and QGJ for the lead which depends on your team that you're running.
I commented on Rey in my last post.
The AI is good in doing worse for Yoda. If he really uses meditation as soon as he has something to share... He will be so much op with Ima... you target him, he counters, get foresight and spread it out :-) As long as that isn't fixed I'll leave him out.
Leia is a solid character but as long as we have the speed meta she is too slow. She always loses a round when stealthing and will come back the next one with a good amount of damage - often too late against speed/dps teams.
A good defense team would be: Dooku, Rey, RG, Dakka and EE. You kill Rey, Dakka or EE will bring her back, possible twice. And you must one-shot her, otherwise RG kicks is. She can almost take out any charakter in one-hit, while beeing protected by the others... but of course there is always a counter for a counter for a counter... but I guess that will be the most annoying team at the moment :-)
