Baizhu is a really decent healer whose abilities scale off his maximum HP, and Kirara is the new 4-star character. I would recommend using Baizhu with Kaveh. However, Kirara is a situational character with Kaveh. He needs field time to detonate the Bloom cores and apply the Dendro element. If you lack a good Dendro character, you can use Kirara's abilities to fill some gaps.