Choosing a framework be it angular, react, ember or vue is personal preference. I would say start with each and build something that utilise state management (todo list perhaps?) and see which style you are comfortable with.
If you wants to get employed, React is a wiser choice. It also helps you build native mobile apps with react-native . If you are building enterprise app with alot of client-side data, nothing beats Ember.js ember-data.
If you are like me who is prototyping light-weight startup and would like to move fast and missing your first front-end learning (angular 1), go with Vue.js . NativeScript-Vue is the binding to build mobile native apps with it.
Responsiveness is an aspect that deals mostly with CSS, and CSS frameworks such as the ones mentioned are focused on addressing this aspect, making it easy to use components in a standard and less bug-prone way when compared to writing CSS from scratch. This said, knowledge of CSS is very important for front-end development, as it is required to customize components provided by these frameworks, and allows you to create more customized and compelling experiences.
Personally, I have used Vue.js, React, Ionic, Angular, and I enjoyed the first two the most, especially React.