5x gear7 Geonosians can beat GW every day with Brood Alpha as the leader.
Bastila is also amazing since her bonus protection regenerates at the beginning of every fight, no matter how much you lost last time.
Brood Alpha doesn't have to be 7-stars. A 3-star BroodAlpha at g7 should be enough with the Geos you have now.
That's fifty shards and some mostly-junk gear and you reach glory.
Battle is almost as easy, but Brood Alpha is a Cantina farm, so you can get the 50 shards there much more quickly than you can get the couple-hundred you need for Bastila.
See, Bastila's bonus protection is based off her health, so you either need to give her a bunch of gear or get her up to 6-stars or so, maybe 5, before a low-gear Bastila is generating enough bonus protection for your high-level battles on nodes 9, 11, and 12. Brood Alpha, though, just gives +15,000 health to every Geonosian, then creates a shard health pool via equalization at the beginning of every enemy turn. Even level 1/gear 1 Genosians have a minimum of 15k health under BA.
For that reason, I think BA is the quicker way to accomplish your goal. That doesn't mean it's the better way, though. If you want to focus on jedi, Bastila is the way to go - as everyone else has already said.