It has always worked out cheaper to buy the phone outright and add a sim only deal, but then you need to cash up front to do that. Although the difference between the two has been decreasing
I don't think that's always been the case. I got my 32GB 4S with The One Plan for £90ish upfront and £35/m when The One Plan sim-only was £25/m at the time. The phone would've had to cost less than £330 to be cheaper going the sim-only route on that particular plan.



Seriously what does an iphone 6 do that a 5 doesn't unless you need the phablet size.