I've enjoyed using DoneJS. It's a lot like using Vue or using React with Mobx. I really like how it provides a lot of things that I'd normally have to set up myself, like SSR, & fall-through data cacheing, and its packager/build tool has the best API of the ones I've used (but I've only seriously used Browserify, Webpack, & StealJS, and SystemJS a little bit, so I can't speak for the others). It supports using React for the view layer, if that's your thing. Also, full disclosure, because of my past experience with DoneJS-related projects, I got a position at Bitovi last year. It's pretty likely you've used sites that use DoneJS tech, too. I know of at least one in the Alexa top 50. I REALLY like the changes of the next version, which is currently available as a pre-release on npm. I've been using it in my side projects and it has some pretty nice changes to many of the APIs.
