Yeah I'm not entirely sold on GraphQL but I think it shines in some cases.

Ex: you are building on top of third party ecommerce software.

You need to add more data to the Cart entity because you have a custom module/plugin/etc. You write a graphql resolver, extend the schema and the Cart type. You can use the existing built-in endpoint to query your new data.

So it's nice to be able to extend a framework and data access in that manner.

In general though, I do prefer REST APIs and then writing custom endpoints if I need data for a specific UI, like for visualizations.