Whoever the newest Gold/Rainbow rank on my team is; I don't gots enuf munny to use them on my favorite level-capped girls OTL

I was using them all on Canola as my favorite unit (and only high rarity pierce), but switched to the new event pierce 5-star. High HP units are my favorite and I really like her first turn burst damage ability. The 5-star abilities really outshine the 4-star ones, so I'm probably going to drop Canola from my helper team eventually, and I want to put ampies on people that are more likely to be in it. I'll go back to boosting Canola eventually though