I use a Pixel 5 with MicroG Lineage OS. I like it quite a bit: it’s fast, has good battery life, and thanks to Lineage OS, it doesn’t spy on me (as much). I do miss having an SD card slot and headphone jack, but those are hard to find anywhere these days, unfortunately.
I don’t have a specific upgrade schedule: I upgrade phones when the need arises. My last phone (Nexus 6) was showing its age: it was slow, the battery struggled to hold a charge, and the USB port was worn out. Switching to Lineage OS and a wireless charger helped with these problems somewhat, but it was still time for an upgrade. My phone before that (Droid Razr M) was stuck in a boot loop, so had to upgrade that, as well.
I have an iPad 3 sitting around somewhere, but otherwise, not much of an Apple person. I try to use Linux whenever possible (I know Android isn’t a traditional GNU/Linux system, but with Lineage OS and Termux, it’s close enough for me).