I had a 4s, and I liked it. Then, not knowing any better, I accepted an Apple OS update. It basically made the phone useless... and that's when I discovered that Apple won't let you downgrade back to what you had.
That was my last Apple phone...
I'm up to the last update that Apple was able to push to the phone... or I think I may have stopped around the time I heard they were "throttling" them down because they want to manage the life of the batteries (although I'm not sure it even applied to the 4S as they were already on a newer OS that couldn't even work on 4S). Anyways, my 4S still works absolutely fine, aside from having a crappy camera and tiny screen, most apps still work. A few apps don't install at all as they need a newer OS to work. The Apple 4S was circa 2011-2012.
My daily driver is an iPhone 5C which is circa 2013. It replaced my other daily driver which was a BlackBerry Z10 (also circa 2013). As an app developer I got both of these phones for free, and I still use them. The only reason I'm not on BlackBerry Z10 anymore is because a bunch of companies stopped supporting apps for that platform... Facebook, WhatsApp, LinkedIn, Instagram, etc... all dropped out. For a while I was "side-loading" Android apps into the BlackBerry Z10 as it could run it, but it was a very old android runtime.
I still use the BlackBerry Z10 for various things as a secondary screen on WiFi, and if not for the crappy battery life, I would still be using it as my daily driver.... because I don't care much for those apps anymore anyways (and I can just use the browser-version). However, since BlackBerry stopped supporting BB10, there have been no browser updates either and so now I can't even load certain websites properly (same happened with their Playbook). Sad since these devices still work beautifully.
So a colleague of mine had an iPhone 6 that developed a screen issue... there were vertical lines in the display which would also affect the touch-screen typing (so certain keys on the virtual keyboard didn't work either). Apparently the wife was in the habit of using the phone right out of the shower, they suspected humidity in it. They were in for an upgrade from their carrier so they were nice enough to give me the phone for keepers as they know I like to tinker with stuff. I opened it up and inspected it, nothing looked damaged. I let things dry out for a week or more, it still gave some sporadic lines and then one day it went back to normal and has never given me any problem since.
I am still using my iPhone 5C but I have the iPhone 6 ready and waiting... which I use for taking photos and filming most of my YouTube videos, on WiFi with various apps, but not my daily driver (although I should eventually switch, I like the smaller 5C in my pocket). So as far as I'm concerned I am happy just collecting old iPhone's from my friends who are ready to toss them out and using them another 5-6 years. That's the best recycling program you could ever have.

Here's a video I did comparing some of the iPhones we have. The iPhone 4S, 5C, 6 are all freebie hand-me-downs and only the iPhone 8 is my wife's that she upgraded to with her phone plan (after complaining about the second free 5C that I gave her to use prior to it). Both of us prior to these were on BlackBerry Z10's, both of which I still have and use almost daily as well:
If I were to suggest... although I'm not an "Apple" person by any means, the fact that I was fortunate enough to have friends/colleagues who bite the bullet on the initial cost but then pass them on to me and now still using them 6 or 7 years later says something. I can't say that for all brands.