When comparing Koa vs CaptainCasa Enterprise Client, the Slant community recommends Koa for most people. In the question“What is the best web application framework?” Koa is ranked 10th while CaptainCasa Enterprise Client is ranked 15th. The most important reason people chose Koa is:
Using generators (a bleeding edge feature, even for Node.js) would clean up your code from the mess caused by all those callbacks; making your code more manageable.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Generator support from ground up
Using generators (a bleeding edge feature, even for Node.js) would clean up your code from the mess caused by all those callbacks; making your code more manageable.
Pro Extremely lightweight
Koa is very lightweight with just 550 lines of code.
Pro async/await keywords are supported and has transcended beyond generator functions
Generators functions are of course a huge plus, but at the time Koa team has transcended generations functions and shifted towards async/await style programming. It has made the Koa best framework available in the market.
Pro Development team has a proven track record
Koa is developed by the team behind a widely used node.js framework (express.js).

Pro Built for ES6
Pro Easy clustering
Pro Very fast dialogs
Very fast even with many controls. CaptainCasa Enterprise client is much faster than Vaadin when writting similar programs.
Pro Fast and powerful
Pro Longlife framework
Pro CDI via EL
Separation of the backend code and the creation of the pages / Injection of the code (CDI) into the pages via expression language (EL).
Pro High security
Pro Server development with Java
No javascript is needed, everything is developed on the server with Java. Optimized roundtrip.
Pro Free use
Pro Good scalability
In addition to the extremely good performance, which already ensures that the system can be scaled well, clustering of the system is already provided for in the software architecture.
Cons
Con Community is relatively small
Con Not compatible with express style middleware
Koa uses generators which are not compatible with any other type of Node.js framework middleware.
Con Has no routes separated by HTTP method or URL pattern
Con Wrong Middle ware, security issue
