What's your take on being 'frugal' with mobile phones? Buy cheap that lasts 2 years, or buy big that lasts 5 years?

Just wondering what you folks think of mobile phones, as I currently need an upgrade. My current phone's old, slow, and battery lasts less than a day. I need it to be consistent for work.

I may need to buy a newer one (mine's from 2017) in the coming months.

Would you buy a cheap-mid range phone that lasts a year or two, or do you gamble on an expensive flagship / last year's flagship that may last 4-5 years, assuming you're careful with it?

I am considering getting an iPhone (or last year's) solely for the 7-year security update coverage that it will get. The longest updates for Android are Samsung's S21s, with 4 years. Every other Android brand has fewer.

If we are talking longevity, surely having software support would be up there?

But I am not really a phone guy, so maybe you guys have a different take on it.