tl; dr: speed, screen quality, external flash drive speed (UFS 2.1), battery, basic water protection, og audio output, . I won’t paint it, everything has been discussed many times in other reviews and reviews.
Details.
I chose for a long time and for specific requirements. I wanted something with the best possible camera at the moment, a normal og audio jack (3.5 mm), a long-lasting battery, moisture protection, a more or less normal atude to safety. And I didn’t want to take the Chinese (especially after a bad experience with xiaomi and more distrust of their firmware). Yes, I only looked at models of the last 1-1.5 years in order to receive security ates for at least another 2-3 years. (Here, android is very sad compared to iphone: an average of 2 years versus 6+; maximum support - for google pixel - 3 years from the start of sales).
Before that, there was a sony xperia z2, on which cynogenmod was rolled out immediately after purchase, which later ordered to live long and frayed by its descendant - lineageos (with afwall + and everything corresponding), but there were problems with it: reboots (spontaneous and with each long charge) , falling applications, etc. In terms of hardware - an excellent phone, worked for 5 years.
A good camera was required to kill two birds with one stone and not buy an additional camera (at least in the near future). On s10+, I decided not to change the original firmware because of the proprietary image post-processing component (the physical capabilities of the cameras are now approaching the limit, now the compeion is in the field of raw image processing software).
Throwing out 3.5 mm (from my point of view) is only a marketing ploy, so that people suffer and then buy new models, where they will return it back. Let's see.