Supabase Auth: We do much more than them — e-mails, organizations, permissions & RBAC, user dashboard, impersonation are some of the features we have. (I like Supabase a lot as a DB — we're working on some fancy connectors to use Stack Auth alongside Supabase RLS, so you can get the best of both worlds.)

Supertokens, Ory: Developer-friendliness and integrations, mostly (both of these target enterprise customers). Also, Supertokens is open-core. I'd say we're to Supertokens/Ory what Clerk is to Auth0.