Vue.js

I was a big fan of Vue 2. Vue 3 is a completely different library if you choose to adopt the composition API (which is where everything is headed). If everyone is going to have to learn a totally new composition pattern, might as well look at what else is out there.

Kinda similar to the big overhaul between Angular 1 and 2

Vue 3's Composition API and composables are more similar to React functional components and hooks than it is to Vue 2 and its Options API. That's not to say that React Hooks and Vue Composables are apples-to-apples. They still have different approaches to reactivity and so on, but the programming model is more familiar between the two.

Coming to Vue 3 from 2 was a bit of whiplash. However I've been working with it for a few days now and have come to appreciate how much more flexible and powerful it is to have access to Vue's reactive primitives anywhere - you don't have to write all your business logic in the scope of a Vue instance.

That said, it comes with a much higher learning curve. Vue 2 gave you guardrails, an easily understood component class structure, etc. That's what I liked about it as it scaled well to large teams. Whereas React scaled to a large team quickly turns into a complete mess. Ask 10 different React engineers and you'll get 10 surprisingly different approaches to how to implement components and architect applications.