- Relay by Facebook, it's own GraphQL client: https://facebook.github.io/relay/
- Urql by FormidableLabs, an effort to build a simple React GraphQL client that covers the 80% use case: https://github.com/FormidableLabs/urql
- GraphQL Request by Prisma, a minimal, universal GraphQL client: https://github.com/prisma/graphql-request
Plus a variety of smaller ones like Lokka (https://github.com/kadirahq/lokka), FetchQL (https://github.com/gucheen/fetchql) and micro-graphql-react (https://github.com/arackaf/micro-graphql-react).
It's all about the tradeoffs you want to make: if you're building a React app your can't go wrong with Relay or Urql, if you're writing one-off (universal) scripts graphql-request is probably your best choice, etc.