What is the best JavaScript Frameworks to learn?

React.js is a library, so you don't get any magic and support from this tool... you have to be very advance in programming to develop a nice app with React.

Angular and Ember are real frameworks, they support all aspect of a Frontend Application, so you can learn more concept if you start using them.

One of the best tutorial for Ember.js is https://yoember.com where you can learn it from scratch.

Not a "framework," per se, but I would suggest #usetheplatform with Polymer.

Outside of that, Vue.js

You actually forgot the best one: Vue.js.