My personal preference would be to pay cash for the phone upfront but there are no discounts for that AFAIK.
I have an S22U so its trade in value isn't very much on a straight trade-in.
The VZW UU plan costs $10 more per month than my current plan but it offers more 5G hotspot data which would be nice. If I understand the plan correctly, which is unlikely, I would also get 4K streaming. I only get 720p on my current "Unlimited" plan.
It would be nice to be able to jump on a newer phone yearly if something about the new phone really made it stand out. The S23U and S24U weren't significantly better than my S22U in ways that matter to me.
I'm only tempted by the opportunity to pay so little for the S25U. I would have to pay a little more over the same duration to get the 5gb storage instead of 256.
I've never kept a phone for as long as my current phone but the S25U doesn't knock my socks off either. I would like the flat screen though. There is no way I would spend $1400 for one though.