It used to be the case that you'd get the phone subsidized by your service plan from Verizon, but not any longer. Verizon and the other major US carriers stopped subsidizing phones in the past few years.

For me the biggest reason I wanted to buy through Verizon was they were offering a promotional $200 trade in value for my Note 4. For some people selling their phone separately would be a better deal though, so even that won't matter.