It's fantastic to live in a world where you want to "learn all the frameworks" or just bounce around when you need it.
But that doesn't produce a master of craft. You don't learn to create a fully scalable SEO-friendly React-based SSR PWA without learning the ins and outs of React and it's inherent limitations compared to other frameworks. It takes practice, experience, and tons of time digging through docs and Medium blogs.
And once you've walked down that road, it takes time and energy to walk down another labeled something like Vue or Angular.
Pick one that you enjoy working with, and make sure you can see yourself getting paid to bang your head against it.
I'd recommend Vue for more frontend based developers. It's easier, and more hands off than other complex frameworks like React. The community has been growing steadily, and it's been implemented by default in frameworks like Laravel, so the demand has been higher in the industry.
If you want more of a challenge, or you want to build a more complex app, I'd recommend picking up React and Flux/Redux/RxJS. React does an amazing job of handling incredibly complex DOM interactions and managing state. And Flux/Redux/RxJS will help you keep your state global across the app.
If you want to build economic JS apps for things like embedding on websites try using Preact, it's a lightweight version of React.
If you want to build cross-platform applications try picking up Electron.
As you can see there are a lot of choices with pros and cons, and plenty of opinionated code decisions. Find one that you can tolerate the most and that you see the brightest future for and contribute to it. No one is a clear winner in the JS framework war, we're all just foot soldiers pushing the frontline further with each conversion and commit.