Flattered you would take this into consideration when phone shopping. To be honest, I would say choose based on other considerations, like how large you want it to be when holding it and in your pocket etc., and how your eyesight is when reading articles etc. I say this because our aim needs to be to accommodate whatever screensize you want to use.
They are saying the next batch of iPhones in the fall will reintroduce a smaller size again. I’m due for an upgrade, and am definitely interested in a smaller phone than my iPhone X! (I love Android too, just too deep in the walled garden of Apple to switch to Android as my primary device).
So… if we can make things look good on a smaller phone, then it should also work well on larger screen sizes. I know that we do have some work to do, for example with the question layout, to reduce the vertical scrolling needed to see a whole question.
I would rather you buy whichever you need for other considerations, then I’ll give you my word that we’ll keep tweaking things until you’re happy with the experience of using the site (or whatever unannounced app may or may not be coming ) on your device.
Curious to hear which phone you choose!