Koa vs FeathersJS
When comparing Koa vs FeathersJS, the Slant community recommends Koa for most people. In the question“What are the best backend web frameworks?” Koa is ranked 33rd while FeathersJS is ranked 35th. 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.
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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 Can sync events between different Node instances
Feather can sync events happening in two different Node processes or even servers in real-time. For example: an event happens in server A, the user connected to server B is instantly notified of that event.
This is done through a central Redis or Mongo collection or through a websocket libraries' clustering library.
Pro Easy REST APIs
Through services, Feathers provides instant CRUD functionality, it also can easily expose a RESTful and real-time API through HTTP/HTTPS and websockets.
Pro Can be integrated in an existing ExpressJS project
Since Feathers itself is built on top of Express (it's a thin wrapper over socket.io, primus and Express) and because of Feathers' highly modular nature, it's very easy to integrate Feathers in an existing Express project.
Pro Plug-in any feature you need
Feathers makes extensive use of modules (which are called Feathers services). These services work like ExpressJS middleware and can be used with app.use('/path', serviceObject)
.
Services help developers keep their applications modular and as minimal as possible, without any unnecessary libraries or bloat.
Pro Support for different socket transports
FeatherJS uses primus which is a universal wrapper for real-time frameworks. Through primus you can easily choose which socket transport you want to use.
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
Con Not so widely used
Could be problematic to convince the client use this framework in his/her project.
Con Not very beginner friendly
Although the documentation for Feathers is very good, it still needs some configuration in order to get Feathers up for developing something with it.
