Answer 1

It depends of projects you are working on.
Also if you will use this to find job, than research job offers and see what company close to you are looking for.

My choice was React, because it have easy syntax, use vanila javascript, also I can learn React Native and build apps for mobile phones(both android and ios)

Check this link to see diference and more about them:
https://athemes.com/guides/angular-vs-react-vs-vue/