We looked at Okta, Auth0 and Cognito when shopping for an identity/auth solution. If you have pretty vanilla requirements then a SaaS solution will probably be easier. Keycloak is not the easiest thing in the world to deploy (although it's pretty straightforward to deploy on k8s using https://github.com/codecentric/helm-charts/tree/master/chart...).

If you need a lot of customizations then Keycloak is great since it has a really robust architecture for writing extensions. It's also pretty cheap to run so if cost is a major consideration it's definitely worth a look.