Use React component library when building out a new product?

What's your take on using a React component library vs not using one when building out a new product?

If it's a small app with simple styles and behaviours then you can certainly roll out your own. At a certain threshold of complexity, a React app requires building out your own component library which becomes too time consuming and you'd wish you started off with one.

You make your call for what the end game is of this product.

Can anyone recommend a good component library?

Most popular:
- material-ui
- semantic-ui
(avoid bootstrap-react)

Thanks for the recommendations. I'm checking our the grommet component library now