Question: Why do you use Feathers JS?
Decision: Because Feathers JS makes it easier to create real-time REST API project with Socket.io or Primus. Besides, Feathers is a tiny, fully compatible, wrapper over Express, a framework that has been used by a lot of people including me in production.
Question: Why do you choose Socket.io over Primus?
Decision: Because Socket.io is used by a lot more people, so I think that if I get any problem in this project, it will be easier and faster to find the solution.