The $60 loyalty plan is only available to existing Verizon Wireless customers, and then only in certain circumstances. This is a customer retention deal
not universally available even to existing customers, and can't fairly be compared with plans available to everyone. The $60 plan from Verizon that *can* be compared is the individual line plan that has a 1 GB data cap.
Now, yes, there are people who have a smartphone and can do with less than 250 MB of data. I'll grant you that. And yes, were the OP looking only for a single line plan and able to keep their data consumption under 250 MB a month, they would indeed have no reason to leave Verizon. But the OP is looking at 2 lines, and T-Mobile there is most definitely cheaper. Even if each of the lines were to never use more than 250 MB each, the plan would still cost them $120 a month (2 smartphones, 500 MB of shared data). A comparable plan on T-Mobile would cost $80 ($50 for first line, $30 for second), and they would save money even after making a payment for a device and be able to use twice as much high-speed data.
But so long as we are doing single-line hypotheticals unrelated to the OP's needs, I'll propose my own: since the $45 plan is the lowest-cost offering from Verizon only suitable for a few, I would argue that the T-Mobile prepaid $30 plan that includes 100 minutes but 5GB of full speed data suits even more people with a smart phone (note: not that it suits even more people, but in the universe of people who use smartphones, I could comfortably bet that there are at least as many people with a smartphone that can do with 100 minutes as can with 250 MB of data. So that would be the plan to compare. We also do not have to assume that the person looking for the cheapest smartphone plan will have to end up with one of the most expensive smartphones on the market (the iPhone). A much more reasonable price point for comparison would be the Nexus 5's $350 tag (which of course isn't available on Verizon). So I'll take the Moto X instead.
Verizon's $45 single-line plan with unlimited talk and text, 250 MB of data, with overages clocking at $15/250 MB.
$1,080 ($45 x 24 months)
$50 subsidized Moto X cost.
$30 upgrade fee
$1160 total cost for Verizon's cheapest smartphone plan over 2 years.
T-Mobile's $30 prepaid plan with unlimited text, 5GB full-speed data, and 100 minutes, with overages at $0.10 per minute.
$730 (The $30 is every 30 days, not exact months, so basically, $1 a day).
$350 full price for Nexus 5.
$1080 Total cost for T-Mobile's cheapest smartphone plan over 2 years.