For me its the ‘Knock Code’ that LG had on their phones (I really wish LG still made at least the V series phones)
Basically there was a four-square area and you set up a sequence of where you would tap to unlock the phone. That set of squares was only shown when you set up the code
Then, to unlock your phone, you would tap those areas in the sequence you set up (even with the screen off).
Fingerprint readers are nice, but I really do miss the knock code
Edit: did find this article with a way to do the knock code, but if done wrong, could brick your phone I guess.
Plus, article is from 2014. When I looked at XDA’s info on it (they also being the developers) it looks like development on it is over, but individual modules may or may not still be supported by their devs
Seems like a backwards move IMO. honestly haven’t needed a tray in ~6 years
That tray is important to me at least since my last couple phones used that same tray to also hold the SD card. I can’t speak for anyone else, but a phone without an SD card for extra storage is a huge NO from me, so that tray is an absolute make or break for what my next upgrade is gonna be.
I find them VERY useful because if you break your phone, you can just swap your sim into a backup immediately.
But honestly it’s not a huge deal, I swapped an esim in under 3 minutes last week