Personally, it took a combination of screen features, camera enhancement, and connectivity for me to upgrade.
I started with an iPhone SE3. I loved it to death cause at that time I was a diehard single camera, homebutton, lighting only kind of guy. I thought apple had lost the touch to their design with the X and had no interest at all in upgrading until 2027.
One day I was in a Apple Store getting support for my Apple Watch SE2 (i liked all of apples old designs besides the airpods) while the 15 Pros were still on sale. I played with the camera, went and checked out the specs later, and then looked at carrier deals. The 16 Pros were just 3 months away, so I scored a half off deal with my carrier.
The optical zoom up to 3x, 15x overall zoom, 0.5x capability, night mode, action button for flashlight instead of the ring switch, much brighter 120hz display for games and outdoor use, 8gb of Ram, increased chip power with A17 Pro, Ultra Wideband support, bigger battery, magsafe and USB-C with usb 3 support, 256GB of storage upgrade instead of 64GB, AOD, OLED, and super premium titanium build while not being massive dimesionally but having a massive bit more of screen, dolby atmos speakers, and dynamic island instead of the all convinced me that this was the iphone the future would have and going to such a solid build would be better for my day to day life at little loss. I still have the SE3 and love it, but the 15 Pro was the right bet. I no longer think the old design was 100% perfect like I once did. The 15 Pro ended up aging better than expected, especially sing its the minimum for all the new features. And having it has allowed me to have so many more moments with loved ones that the SE3 simply wouldn’t have been capable of.
If I could put it in one sentance, it would be if the phone can tangibly make my day to day life eaiser and richer. The 15 Pro certainly did that. And I’ve yet to see a phone that can match it for my day to day life. I’ll be getting a new battery in the fall since I’m at 91% health with 600 cycles, and I’m gonna keep using it until either the Air line, if its continued, gets zoom on par with the 15 Pro, or the 20th aniversary brings something absolutely groundbreaking, especially in camera and battery and screen tech. If neither of those then it’ll be whatever Apple has in 2032 that matches my needs best.