It depends very much on the language/server you are using. In Rust, IMO GraphQL is still the best, easiest and fastest way to have my Rust types propagated to the frontend(s) and making sure that I will have strict and maitainable contracts throughout the whole system. This is achieved via the "async_graphql" crate which allows you to define/generate the GraphQL schema in code, by implementing the field handlers.

If you are using something which requires you to write the GraphQL schema manually and then adapt both the server and the client... it's a completely different experience and not that pleasant at all.