I haven't "mastered" React by any measure, but I've been using Angular for quite some time, and I find that apps written with it become really frustrating to maintain after a certain amount of complexity. I see Angular somewhat akin to C++ in that it's the most powerful and flexible (IMO) of the popular JS frameworks, but you're also going to spend a hell of a lot of time creating your own structure and conventions. This is a fine tradeoff if you need the flexibility, but for my use cases, React is much simpler and less headache-inducing to use. I just find that I can fit React's model into my head, whereas with Angular I'm constantly needing to figure out how to translate my mental model of my app into code that actually works, and dealing with weird, undocumented edge cases.