Use ship currency for ship shards? Or toon shards?

Recommend good toons for fleet if they r there and rare ships that r good like boba and mauls ship but they rarely show. I use fleet as means to farm toons I need that might be in cantina but I farm one at a time from there so I can work on 2 at once that r in same area ship upgrades don’t do much until 5* which cost like 500k ship currency anyways so u basically r just farming to 3* for ship events at this point I’m lvl 74 I go up to ranked 2 during shard time close to boba ship now might get in few days if it pops up in store and I’m lucky maybe farm 3 shards without it a day