It also depends on the model. The newer iPhone you get, the better the scanner is.

And, in case you did not know: it’s a 3D scanner, based on a technology similar to Microsoft Kinect. Presenting a 2D photo of your head won’t work. Presenting a 3D printed, but uncolored copy of your head would not work either.

Yeah, you have to rise your head every time.

Btw covering the same percent of your face horizontally doesn’t cause any problems.

Camera is way better (although some people find it overprocessing). Try before you buy.

Dynamic island is cool.

Overall more recent CPU - more smooth UI, also means the phone will be supported a bit longer from now.

Ties to iOS ecosystem (watch/airpods/magsafe stuff), build quality, longevity, support, better privacy (since Apple makes money from you, and not from ads), better software quality (due to stricter AppStore guidelines). iMessage, FaceTime, AirDrop. Also habits.