When comparing Kuzzle vs GraphCMS, the Slant community recommends Kuzzle for most people. In the question“What are the best alternatives to Firebase?” Kuzzle is ranked 3rd while GraphCMS is ranked 13th. The most important reason people chose Kuzzle is:
Supports REST, WebSockets and MQ protocols.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Multiprotocol
Supports REST, WebSockets and MQ protocols.
Pro Realtime through filters
You do not connect to classic rooms but to search filters and can be warned of changes on permanent storage or volatile one.
Pro Open Source
Kuzzle is open source and it's released under the Apache 2 License.
Pro Javascript SDK
A fully documented javascript SDK exists.

Pro Webhooks
Webhooks enable you to trigger custom code as soon as your content changes.

Pro Image processing
On-the-fly image transformations, such as resizing or cropping just by adding parameters to your media´s URL.

Pro Roles and permissions
The roles and permissions feature allows you to assign your collaborators different roles, such as Developer, Editor and Collaborator.

Pro Multi-project management
You can manage multiple projects and create up to 50 users per account to help manage those projects.
Cons
Con May have issues since it's stil la relatively young project
Kuzzle is (as of February 2nd, 2015) in alpha version and approaching beta.
Con Not open source

Con No content versioning
