Swgoh farming flowchart

STOP HERE. From this point forward, characters and ships available in the fleet store are not critical for different events. At this stage, you can, and should, consider investing into Omega and Zeta ability materials for squads you've been working on. Zetas and Omegas come pretty slowly, and make a considerable impact on squad effectiveness, and the Fleet Store will help expedite those upgrades in a big way.

That said, if you'd like to push forward with shard grinds, here is the next pair:

Clone Sergeant - Phase 1 and Mace Windu