Choose PlanetScale when a monthly cluster price and schema branching are what you want to budget. Choose Vultr Managed PostgreSQL when a single node from $15/mo in a Vultr city is enough.
PlanetScale
Managed Postgres and Vitess clusters sized by SKU
Paid clusters
Strengths
Cluster price is a monthly SKU, easier to budget
Schema changes can ship through branching
Limits
There is no permanent free cluster
You pick a size instead of paying only for idle time