I'd say react.js. It has been proven to be a good choice for all kind of web applications (small, large) and even static web sites (https://www.gatsbyjs.org/, https://github.com/nozzle/react-static). Also it has an awesome community and awesome tooling (create-react-app), which allow you not to bother with "framework/library/build tool/transpiling hell".

Check this repo if you're interested in react: https://github.com/enaqx/awesome-react

You can also check vue.js, I have heard from many people that it's very good and some even say that it is better and easier to get started with than react :) I've never worked with it so I can't say much about it