Who to farm in cantina nodes?

Personally I would do JC or any other toons you think are cool. Like you said QGJ is the main goal, so it doesn't really matter.

I see many interesting toons in cantina nodes, but not Windu. Among the Jedi you have JC and Barris (both good for the Yoda event AND the GW). And then you have Kylo, GS and Dooku among the attackers.

I think the choice is personal. But not Windu.

GS hands down. He fits in to so many teams. Other nice options to me are Dooku, Lando, Kylo to name some.

GS is doing work for me in both arena and GW.

GS is for the people who want to follow the wave super op chars that make no fun to use. You got other options, Kylo, Mace who isn't so great but its Mace Windu and Im sure he might get an additional buff, not a crazy one tho. As well as Dooku, but hes the last battle. I farmed Kylo all the way to 7. I think he's great, and I'm farming dooku now. I used my points to get 5's first. To me hes a hidden gem, and now I'm doing QGJ.

GS, JC, Barriss all good. GS seen in most competitive Arena teams I've found. Barriss good for GW and Yoda fight, as is JC. But I'd prioritize JC and GS over Barriss. I stopped farming Mace at 5*, only to enable Yoda - he's not useful really for any other purpose.