And further to the above, what to you sign in to Tailscale with? (Yes this applies only to a subset of people who care about Tailscale.) They don't want to be an identity provider so they don't offer an email account type. You can choose from Google, Microsoft, GitHub, Apple, or OIDC. In theory, you can choose something else that provides OIDC; in practice, I don't know how well that actually works.
Email, using my domains for nearly all things. The one exception is a dedicated purpose gmail account for talking to one specific Youtuber.
I'm trying to work out how much it really matters to implement social auth.
At the moment I have implement email signup into my application and so far I don't really see much value in implementing social auth if people are happy with email.
Pretty much like the other comments, unique email with my own domain, I am in control, plus, I don’t use or trust social media / corps for anything, let alone to access other services, and that includes github login too.
Email @mydomain.tld
Otherwise, Google/Facebook/Whatever can lock me out of the web.
If I trust the website, email. If I don't trust them oAuth. oAuth implementations don't give the developer my password and generally disclose any permission red flags.
Unique email address under my own domain for each service. Don't have a Google/Facebook/whatever to auth with anyway.