I have a question related to your recent security series.
In your opinion, what is the best way (most secure way) to use 2 factor…SMS, Email or an Authenticator app? And can you even use an Authenticator app on with Apple accounts like Apple ID?
Authenticator app since the code can't be intercepted in any way. But any one of those is so much better than no two-factor at all.
With your Apple ID (iCloud account) you are using the same technique as an authenticator app, but it is built into macOS and iOS. Notice that you get the two-factor code as a special window that pops up on your Mac and iOS device screen.