What Apple has successfully done for me is create an infrastructure that makes it difficult to contemplate changing brands. Everything in my life is well-integrated to the Apple infrastructure - my watch, my headphones, my lights, my thermostat, my garage door, my speakers, my car, etc., etc. On top of that I’ve got a decade or more of App Store purchases. It wouldn’t be impossible to change, but it would take time and money.
That said, price aside I’ve been happy with Apple. The phones have always been solid and I have had little reason to complain outside of some bugs here and there that come around as part of their yearly upgrade. That said, I don’t have other smartphone experience to compare my phone to - I’ve been on an iPhone since I switched from some old Nokia flip thingy many years ago.
As for upgrading, I tend to do it if there is some sort of trade-in deal or special sale on a newer model. What I mostly look for is camera improvement. I used to enjoy photography as a (very amateur) hobby and would lug around a bag with my DSLR and a variety of lenses whenever I would travel. The phone can’t replicate that, but with kids (and a sometimes impatient wife) it has become more and more difficult to carry all that gear and the phone is simply more practical. With cameras and processing continually improving, it takes the sting out of not having my gear. It will never replace my good telephotos and wide angles but for the vast majority of the pictures I take these days it is acceptable.
I always go for the highest storage options even if I never use them. Im already paying a boatload for apple products so I go ahead and pay a little more, I suppose. I’ve never needed the full storage, but in the past I’ve had limited storage on some of my devices like a 16 Gb iPad that did fill up quickly and it was quite annoying.