Verizon owns 700(LTE), Cellular 850(CDMA/EVDO), Some PCS 1900(CDMA/EVDO) but not nationwide, and AWS.
700 travels the furthest, but they only have enough spectrum for 5Mhz upload and 5mhz download FDD carriers.
They have the most AWS, so they can deploy a really fast network on it. 20×20 if they wanted to in most places in the country.
Since most phones don’t have AWS and they don’t have a ton of 700, their 700 network is really starting to slow down. If you’re on Verizon you’re really going to want a phone supporting AWS!