Spring-boot vs Play
When comparing Spring-boot vs Play, the Slant community recommends Spring-boot for most people. In the question“What are the best web frameworks to create a web REST API?” Spring-boot is ranked 3rd while Play is ranked 31st. 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
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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 Good documentation and a great community
Play has quite a large community which provides numerous tutorials and videos related to developing with Play.
The Play official documentation covers many things, such as the framework itself but also specific stuff such as Akka, SBT and Netty.
There are also many big companies that base their main sites around Play, one of them is LinkedIn which provides third-party documentation on a regular basis.
Pro Readable code
Play framework's convention over configuration methodology makes most Play projects have a very similar structure. This means that the code written for the framework is very readable. This enables a developer to switch between applications without having to relearn the ecosystem for every project. The built-in templating system also helps with code and makes it possible to have a very low count of lines of code.
Pro Simple for beginners
Play is very simple to get started. The documentation is very helpful for beginners and advanced users alike and the official website has a great "Getting Started" tutorial to begin developing with Play.
Pro Play feautures Non-blocking I/O by default
Play Framework is asynchronous from the bottom up: asynchronous is default in Play API.
Pro Play is an extensive ecosystem
Play uses Akka for concurrency, Scala for a templating engine, Netty as a client-server framework and SBT (Simple Build Tool) for building. And they all come out of the box.
Play also comes with the option to scaffold your applications. Play is an all-embracing ecosystem designed to increase developer productivity and shorten development times.
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 Awkward, non-idiomatic Java API
Con Backward incompatibility
The jump from Play 1 to Play 2.x caused a lot of confusion. While it is important to have some kind of evolution, sometimes it causes backward incompatibility which can create some problems. It makes tutorials or modules made for the old version obsolete. This can make it hard for beginners to find useful resources. The template engine which used Groovy now uses Scala.
