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
Small sizes
Multicolour notification LEDS - customisable for each app
Smaller camera bumps and less cameras in general - not everyone wants or needs to be a professional photographer.
Plastic bodies, with removable batteries via covers.
I don’t know how many current phones support it but mine doesn’t… Extendable storage via micro sd
Customisable vibration patterns for different contacts and apps - I remember how super old early Android Xperia phones being able to do this (alongside the LED mentioned above). I used to think this was stock android, I guess not. But if it was, why did they remove it, same guess for LED
Sony still uses multicolor notification LED in their phones.
High quality plastic bodies are so good. Hard to break and easy to repair. I hate glass bodies.