EDIT: this answer focuses on graphql java servers as you mentioned spring-boot. If you are after graphql java clients, I would recommend the Apollo Client, it is easy to use and does everything you could need.
Disclaimer: I have never used DGS, and I have not been using graphql-java actively in the last year, things might have changed. I have tried graphql-java-tools and spqr. This answer is opinionated.
The graphql implementation graphql-java was around before DGS. It is open source and you will find many project have been built on top of it. Projects that add features to graphql-java itself can be found in the graphl-java repositories, making graphql-java quite modular and adaptable to your needs.
For example:
Graphql-java is quite verbose, and I would not recommend using it as is. Instead I would recommend using one of the following projects.
https://github.com/kobylynskyi/graphql-java-codegen generate your graphql server/client from your schema, following a schema first approach
https://github.com/leangen/graphql-spqr or https://github.com/Enigmatis/graphql-java-annotations follow a code first approach and makes a very efficient use of annotation to generate your schema from your code (spqr also provide a spring-boot starter)
https://github.com/graphql-java-kickstart/graphql-java-tools use a schema first approach and that let you create your own DTO. It takes care of most of the boiler plate code. It is Spring friendly (if used to the Spring framework, the graphql-java-tools resolver will be very intuitive), and has a spring-boot start. The schema parser and class discovery are powerful yet modular.
Features
In term of features, all those projects leverage the feature of graphql-java, they will be very similar.
Active development and community adoption
graphql-java-tools was updated yesterday, spqr and graphql-java-annotations last year, graphql-java-codegen in January. From reading stackoverflow questions, graphql-java-tools and spqr seem to be the most popular - but I could be wrong.
Limitations
None that I can think of.
Ease of use
SPQR wins that one for me, the annotations are really intuitive and will get you going super quickly. There is also a spring-boot-starter and a few sample projects.
graphql-java-tools is a bit more complex but they have a good documentation and sample projects.
I would recommend SPQR for smaller/new projects and graphql-java-tools for bigger projects or existing projects that needs to build a graphql-api on top of an existing code base. For my personal projects, I moved to SPQR and never regretted it.
Open Source
All the projects referenced in this answer are open source.
Final word:
I think the code-first approach (define your api in java, let the library generate your schema) or schema-first approach (define your api in a schema file, let the library generate your code) is probably the most important factor in deciding which library to go for. You can read my answer and Kaqqao's (SPQR author) excellent answer to learn more.