We have a requirement for a project and we are planning to use the User management and authentication service of 'Oauth2'.
Our application will be on AWS so we also wanted to check with AWS Cognito.
Could anyone help us decide, which is the better option to go with?
I would proceed as follows:
Build apps in a standards based / portable manner, via certified open source libraries
Start with Cognito and see if it meets your requirements / identify it's limitations. Avoid vendor specific libraries unless there is a good reason.
If you need to switch vendors you will be able to do so quite easily, since your apps will not be locked into AWS
Out of interest I built all of the samples on my Quick Start Page using Cognito. It is a good place to start because it is stable and low cost.
As a rule of thumb, no vendor solution works perfectly - there will always be gaps between what you want and what they provide.