We started using CoffeeScript years ago, so the switch to ES6 is quite natural in our team. ES6 of course advances the JS standard to a level of an advanced language. We are using it today simply because it: 1. helps to keep the code shorter, 2. integrates easily with JSX, 3. helps to deal with immutable using const.
React is choice number 1 when it comes to JS development at Kurzor. We choose React because it solves many issues with web applications in a elegant way. Writing an app in components is useful for coordination and isolation of concerns. React forces you to abandon state and use vertical passing through props instead. And having as many Pure Components as possible helps to write cleaner code.
With React we usually use: Redux, React Router, React Toolbox, Styled Components.
React Native is great in that it reduces the overhead of writing native code based on a web app. If written in a good style, Redux part of the app can often just be copied or shared in the Native app - and it just works! What a timesaver.
We love functional approach to writing apps and Redux is thus the premium choice in this matter. The inner beauty of the state tree is unbeatable. We recently learned to solve common tasks via middleware. And the Redux Chrome extension is such a marvel - our developers request extra monitors just to have it nearby.