Rebels have such good characters that there is no one right answer. I typically switch mine up between:
-Jyn Lead
-Wiggs
-Chaze
-Wedge Lead
-Biggs
-Jyn
-Emp Palp
+ A healer (rebels are pretty squishy health wise but with a wedge lead they regain health almost every turn soooo....feel free to sub this out for another toon.)
Believe it or not Palp & Jyn have worked incredibly well together for me. Once Palp mass shocks Jyn comes in with her Truncheon Strike and robs their turn meter before they come out of stun leaving them stunned for another turn.* There are ways around this however which is why I always target cleansers first. *