Why is Angular so less popular than React?

I've used both for non-trivial apps. I find angular heavily over-engineered. The problem is not just the learning curve, but the fact it becomes almost impossible to do anything the framework authors didn't envisage. React is just plain functions so you can do whatever you want, it never got in my way.

Now, if angular would prove substantially better in terms of performance or maintainability or so, that might've been ok. But they're not. Performance is on par, I find refactorings actually harder because of the heaps of boilerplate angular requires, etc. They invented way too complex solutions to solve problems that either don't exist, or other frameworks solved better.

I am curious. I have never used Angular or React seriously. But I have an upcoming project where I have to use an external HTML Canvas library.

Would you suggest I go with Angular or React?

It's a fairly complex project, involving user based label designs, data manipulation, etc.

I am API based server and a heavyweight front-end.

React and angular basically both do the same thing: render a component tree to (usually) the DOM. You use a framework to make this easier for you and I think react does that way better. But if it's all about raw data manipulation and using that canvas lib, you may not need either?

Never used it myself, but the guys from Flipboard made this react canvas renderer which might be useful for you: https://github.com/Flipboard/react-canvas