1. AngularJS :
The popularity and power of backbone can be judged from the fact that biggies like Pinterest, Foursquare, Walmart, Disqus and Delicious are using backone.js.
4. Polymer js
Polymer gives powers and brings structure in building custom HTML elements using browser based technologies that includes web components.
5. Knockout js
Knockout works under the MVVM design paradigm and that makes it a little different from Ember and Angular.