Clerk: when you want the easiest setup and don’t expect too many users
Though I haven't tried it out, I'm sure Clerk is super easy to implement from what I've seen, and it seems powerful too for User management. The only gotcha for me, and it's a big one, is the price. I think it's less expensive than Auth0, but still, $0.02 for each MAU is very expensive if you have tens of thousands of users and you want your app to be free for your end users. I would probably consider Clerk to build a B2B application, where I wouldn't expect too many users, and where I would need extensive features for user management.