I chose Angualar due to having the largest community, biggest backer (Google), and the positive reviews. I'm a huge fan but sometimes think there's a bit too much "magic" happening. The worst part however is the learning curve, which can be brutal for new javascript devs. Still, the more I hear about Angular 2.0, the more I realized AngularJS was the right choice and will be the dominant framework for the web moving forward.