“Best” is kinda relative. React and Angular are the big two, with Vue third (and popular). Huge communities of users, lots of documentation and tutorials. In comparison, Ember isn’t very widely used and the community is much smaller, so more difficult to find help. Backbone works but isn’t used very much nowadays; it’s generally been superseded by other frameworks.
Any reason for that or just personal preference? There are plenty of jobs for Angular, so it’s certainly a solid choice in terms of career prospects.
@humandev really it comes down to what you want. IMO React or Vue are good places to start, as they’re relatively light-weight. Angular and especially Ember are very full-featured and can be a bit overwhelming if you just want a view library. Backbone and Meteor are less popular choices these days, I wouldn’t recommend starting with one of them unless you require it for a specific job.