I recently decided that I wanted to learn a full stack. MongoDB, ExpressJS, and NodeJS were chosen without question. Now the question of Angular v Backbone v Ember comes in. Here's the stats I have gathered so far.
GitHub

Angular: 24,431 Repos
BackBone: 13,721 Repos
Ember: 6,037 Repos
Reddit

Angular: 5,415 readers
BackBone: 553 readers
Ember: 1,117 readers

Google Trends