I pay about £15 pcm for unlimited data and more of everything else than I can use. I buy a phone when I feel like it, usually about every 18 months to two years. Currently very happy with my P20 Pro. Advantages (to me) are that I can switch network whenever I feel like it, and I own the phone from day 1.
I put the unlimited part to the test as well, using it as our home broadband for a few months. 100GB+ and they didn't squeal.
(--edit-- looking at the invoice it's a mess of charges, bonuses and weird discounts, starting at a base price of £34 plus vat, brought down to £17 plus vat, not quite as cheap as I thought and a lot weirder)
Looking at what I have on my invoice -
£34 - Business 900
£4.167 - Landline 1000 (this on is weird, I have no landline from anyone)
£4.255 - Broadband Plus (I also don't have broadband from them)
-£8.511 - '25% Recurring discount'
-£16.667 - 'Loyalty discount'
Coming out at £17.286 for the lot before VAT, I'm assuming the guy put on some basic charges for the lowest level landline and broadband connections, which were never to be provisioned, to unlock the discounts ... !I don't get an iphone, but it's a fair bit cheaper...
Sure there is stuff that's better now for games or really pushing it. But for taking some pictures, navigating, podcasts, notetaking, general admin, youtube, messaging etc etc it's still absolutely fine.
I've actually just bought a Moto G6 Play and that's an extraordinary device for the money (£129.99).
4000mAh battery, bigger screen (though not 'better') and can do all the S7 does above without trouble. Camera isn't as good but man it's cheap for what you get.
I find this to be hilarious for reasons I can't quite articulate but going from a model where service is decoupled from hardware to a model where you're contractually obligated to pay a set bundled fee is a 180 degree switch too inexplicable to ignore.
But these days, those expensive plans have 20-30GB a month, whereas I'm still only using the data I was back then, and you can get plans for $20/mo for 4-6GB. So I've now gone to buying the phone outright and getting a cheap plan, and save a ton of $.
I suspect a lot of people are still under the mentality that they need the amount of data included in the more expensive plans, without ever checking that to be the case.
Of course, if you're streaming YouTube/Netflix/music at the high bandwidth rates and not even doing the bare minimum to pull down that data while on WiFi, all bets are off.