React has an unfamiliar syntax and the cognitive load to "get it" while not huge, was going to take time.
Angular seemed fine but a little verbose and a new version was coming out that diverged from Angular 1 in a way that caused more than a few headaches, apparently.
With Vue.js I read through the excellently presented guide and started building my app, instantly.
I view building an app (or app based business) as lego. Join all the pieces together and yay, you have a product. Vue's component based approach matches that perfectly.
Then you look at the small number of open issues on Github, the large number of Vue.js components available (https://github.com/vuejs/awesome-vue), the well-thought-out error messages, documentation and chrome dev extension.
That adds up to a refreshingly pain-free dev experience. As I've mentioned here before, it's so simple it feels like cheating.
Maybe because I have a background in functional programming, it only took me an hour or two to get React itself. The basic concept is dead simple declarative programming: declare a React component some state, and it renders it. The lifecycle adds a bit more to understand, but most of us have dealt with lifecycles somewhere, whether in WordPress, Android, etc. And then there's local component `state`. But that's it.
However, what's commonly accepted as the React ecosystem (meaning webpack, babel, flux/redux, eslint, sometimes flow etc.) takes a lot longer to understand. And can be quite (perhaps overly) complex.