I don't know where you are but on the east coast, I've found Sprint's network to be excellent. I've found the VZW network claim to be a lot of hooey that people buy into. It almost always comes into play where it's a matter of (a) GSM v. CDMA and (b) specific parts of the country that are not major urban/economic areas.
I can't speak of the reliability of Sprints network, bit I can speak of the speed. It has been recorded that the 3g VZW network is actually faster than the Sprint 4g! Sprint (and to some extent, at&t) rushed their 4g networks out to be the first networks with 4g. 4g and 3g was originally supposed to have a similar difference that you see in DSL and cable internet. The companies changed it to a definition of "anything faster than 3g". VZW took its time and did it the right way, now the other networks are struggling to keep up. This is also why VZW made sure to advetise the LTE part of 4g, as the other carriers dumbed down the original definition of 4g. Anyways, 4g doesn't have a definition anymore to many people, but LTE definitely does!