Offering my personal opinion on the matter, since I've used all three of the most popular libraries in large-scale projects. Angular takes a lot of work to get to know with no real payoff. Comparing the architecture to the other libraries, it's not as intuitive and it's not as easy to maintain; things that are easy elsewhere are often tricky or weird in Angular. I'm sure there are great developers doing good work using Angular, but in my experience it's easier to onboard people and MVP things using other tools.

But we don't know if people mean AngularJS (1) or Angular (2+) here. In my opinion, while angularJS is now getting a bit outdated and very different under the hood, for a user it's pretty similar to Vue.JS, which people do seem to love. Angular 2+ on the other hand seems to have added a layer of JavaEE-like over-engineering on top. I think a framework should be written with productivity as top concern and Angular 2+ is anything but that, it constantly works against you.

My bet is that Angular pushes for using TypeScript too much, which makes you wonder where to start. On the other hand ReactJS & Vue work with TypeScript, but are not designed to embrace it.

I've seen lots of questions about Angular on StackOverflow which should be classified as TypeScript questions, since they have nothing to do with Angular itself. I guess that's the confusing and non-attractive part of Angular.

TypeScript is awesome and I love to use it, but some of my clients ( freelancing ) don't want me to write TS code, since they are afraid that it will be harder to find a substitute and will increase complexity - both are reasonable arguments.

Angular reminds me of the Spring "framework". Once you peel back the GIGABYTES of framework redirection and figure out what it's actually doing, it's not a bad way to organize code - it's just that trying to wrap that up in a reusable library rather than just recommend it as a best practice is so braindead as to be incomprehensible.

Wasn't there some kind of huge upgrade pain between versions (v1 to v2 I think it was) for people?

I vaguely remember talking with some folks at work who were trying to upgrade at one point, and they ended up changing frameworks entirely (to react) because the effort to upgrade was considered "about the same as a rewrite".