Ask HN: What do you use for user management/IAM in your SaaS app?

I have been trying to figure out what that one(or more) IAM solution I can use for building a SaaS application with the following features:

1. True multitenancy - Concept of users/organisations 2. SAML/OIDC/Active Directory connect 3. Multi-factor authentication 4. RBAC/ABAC access control model 5. Session management 6. Social sign-on 7. Low management overhead 8. Modern UI/UX

I want to optimise for the lowest total cost of ownership over 3+ years, and aim for 10-50k users. The market is filled with IAM products, some of them are:

1. Keycloak (OpenSource) 2. Supertokens (OpenSource with paid plans) 3. Supabase (OpenSource with paid plans) 4. Authelia (OpenSource with paid plans) 5. Authentik (OpenSource with paid plans) 6. Logto (OpenSource with paid plans) 7. Clerk (Paid) 8. Zitadel (OpenSource with paid plans) 9. FusionAuth (OpenSource with paid plans) 10. Stytch (Paid) 11. WorkOS (Paid) 12. Ory Kratos (OpenSource with paid plans)

Every time I ask Gemini/Claude/ChatGPT/... to do a deep-research and give me one recommendation for a tool from here, I get a different answer, with different rationale. I have also read so many articles for both very high praise and very staunch criticisms of all of these tools. With so many options around, which one do you choose, why, and how is that decision coming along so far? Thank you.