Spring-boot vs Ninja
When comparing Spring-boot vs Ninja, the Slant community recommends Spring-boot for most people. In the question“What are the best Java MVC frameworks?” Spring-boot is ranked 1st while Ninja is ranked 6th. The most important reason people chose Spring-boot is:
Boot is just a thin configuration layer over Spring Framework, as such it inherits all the strengths of Spring.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Inherits all of Spring's strengths
Boot is just a thin configuration layer over Spring Framework, as such it inherits all the strengths of Spring.

Pro Preconfigured starters

Pro Fast prototyping
Spring boot is built for fast prototyping.

Pro Kick down to Spring
Pro Simple set up
Once dependencies like maven are installed it is up and running in minutes with one simple command.
Pro Easy horizontal scaling
Ninja is stateless by design. This makes horizontal scaling very easy and just a matter of adding servers.
Cons
Con Lacking in UI development
While actually very good and with a very complete and rich feature set to develop and maintain code on the server side, it still doesn't provide any rich framework for building good user interfaces.
Con Little user choice in organization
Since most of the code and folder structure are automatically generated, this leaves little room to the developer on how they will organize their project.
