I never had an issue with Touch ID but that’s because my fingerprints are very readable. My dad has barely any fingerprints so he can’t use Touch ID either.
The Face ID strangely works in darkness for me but struggles in low light. I don’t know if that’s normal but it’s a weird problem to have. I guess you can also say that Face ID works great when it’s wet whereas Touch ID doesn’t work at all.
I've never had a problem with Touch ID. Sure, maybe a few times with a wet finger, a known issue. I've otherwise found it to be completely reliable.
I've found Face ID to also be reliable within its operating parameters. It recognizes my face, only when my eyes are open and when I'm looking at the screen. It works in the dark. I've got an Apple Watch, so for simple unlocking it works with a mask on currently (though that will be more usable once 15.4 comes out), though not with sunglasses.
What I don't like is that I found Touch ID more naturally usable than Face ID. I am a diabetic, and it's normal for me to have my phone set to display my blood sugar when I'm in bed reading at the end of the day. To get to that data, with Touch ID, it was pick up the phone (at any angle), press the home button and leave my thumb there. Now, I need to touch the screen (I habitually leave "raise to wake" off), raise the phone to an angle where it can see my face (which is a very wide angle, but it does have limits), and then swipe up to see the screen.
This dynamic is at work as well for other unlock situations. It really makes a difference for Apple Pay, which was simplicity itself with Touch ID (hold phone to terminal, place thumb on home button), and is more of a PITA with Face ID (double-press the side button, hold the phone so it can see your face, then place to terminal). Part of that is the double-press: I find it unnatural to do it without accidentally taking a screen shot. Even taking for granted that muscle memory will someday overcome this, I think this is still significantly worse. So much so that I now do Apple Pay with my Apple Watch instead. Not because I found it a more efficient or satisfying way to do it than Touch ID, but moreso than Face ID.
There is one class of interaction where Face ID is definitely better than Touch ID: authenticating inside an app. In those situations, however, I'm already interacting with the app, and so already looking at the screen. It's seamless at that point because I don't have to transition to that position, I'm already there by nature of what I'm doing. This doesn't help with in-app purchases or any other interaction with Apple for purchasing, because that requires the side button.
I am slowly getting used to some of this on my iPhone 13 mini. I got the mini so I could get the (much) better camera than on the SE 2020. I don't expect the rumored SE 2022 to have better cameras than the 2020. So I'm calling my switch to the 13 mini a wash, so far:
MINI vs. SE 2020:
Cameras ++
Size +
Battery ++
Screen size - or even
Apple Pay - -
Face ID/no home button - -
It's close enough that depending on the specs of the SE 2022, I would consider going back to it.
I don't believe the shortcomings of Face ID are fixed with an under-screen fingerprint reader. Much if not most if not all of the benefit of Touch ID over Face ID is the presence of the home button, a physical landmark I can find without looking at the phone.