Get the best you can afford. If you plan to keep it for years like you say, you wouldn’t want to go too far back in generations. iPhones are a pretty safe bet since you can really get 5+ years out of them if you really want to.

I went from an XS Max to a 14pro. If I really wanted to I could have continued to use the XS max for at least another year if I got a battery replacement. That phone came out in 2018 and is still supported