I generally just buy whatever phone I think is best at the time. I've had most iPhones, but also Galaxy Note 2, Note 5 and the Z Fold2 (for about a month anyway). I had a HTC phone I can't even remember the name of as well.
I still really want a z Fold3. But i'm so embedded in Apple world now that it might be a bit of a dumb move. For a start I wear an Apple Watch so that'd have to go. I have an iPad and Apple TV as well. So really I should just get the iPhone 13 next month. But it doesn't really interest me. It's just going to be faster, with modestly better cameras and 120hz screen. The 120hz is nice but nothing crazy. The z Fold3 offers something totally different and the big screen is a game changer for me. But do I want to pay that much for it and also essentially nerf all my other Apple products... ?
I wish I could just fast forward to 2025 when Apple release a folding phone and pretend they're the first to do it.
edit:
I actually have this theory that I do not perceive the 120hz difference as much as other people. I am generally a huge display nerd, and while I do like the 120hz on my monitor and iPad Pro, it doesn't blow me away. It's a moderate improvement over 60hz. I've restarted my PC causing it to default to 60hz before and not even realised for a few hours of desktop use. Whereas when I see other people talk about it, it seems like 60hz causes their eyes to bleed.