I had the same experience as Brent Maxwell. Worked in the past with Auth0 and on my last project I'm working with cognito and it's really painful.

If your use case for the auth provider is pretty simple you can live with cognito, but if you need to do even simple stuff like extending the user with some extra data or searching users cognito is not recommended at all.

The only good part on our end is that we have an entire AWS stack so it's all "integrated".