For new SPAs Ember rocks. Also keeping up with the latest and greatest Ember is a breeze. I would not however like to refactor an existing front end application to use Ember. Probably React is better suited for integration with existing front end applications.

Although Ember really feels like idiomatic Javascript to me and they try hard to adhere to new web standards (e.g. web components, ES6 modules) it is also very opinionated about what should go where and how.