I used to think I wanted FaceID over TouchID, because TouchID would regularly fail to recognise my thumb if I'd recently washed my hands, or was a little dehydrated. Anything that affected my skin tension.
In practice, FaceID fails way more often, and also "resets" (the phone decides it wants a passcode before it'll trust my face again) multiple times a day. TouchID almost never did that.
If you have an Apple Watch, you can also configure it to unlock your phone automatically when an obstruction prevents Face ID from recognizing your face.
I'd never go back to Touch ID. Face ID works in the dark, at pretty much any angle, and requires zero interaction.
I have had it in this mode for years. It's still very fragile and/or skittish regarding making me use my passcode. Intuitively, it feels like about 10-15% of logins require the code rather than my face.
> If you have an Apple Watch, you can also configure it to unlock your phone automatically when an obstruction prevents Face ID from recognizing your face.
That's a very expensive solution.
> Face ID works in the dark, at pretty much any angle, and requires zero interaction.
All of which apply to TouchID too.
Especially since it makes many operations a 2-step process when it was much smoother before; like for example Apple Pay where you find yourself looking at your phone like an idiot instead of doing it all in a single movement.