I’ve never had Verizon, but I know that in my area T-Mobile is superior to what I had with sprint. See this bgr article.
I would say no. Verizon has better coverage once you get out of the main metro areas. However, no cellular carrier has coverage everywhere, so having access to WiFi calling without a lot of monkeying around is a big help.
When I had Verizon in my are many years ago it was not that great. I think they have improved, but AT&T is the best. It is really sensitive to where you are though. I could go ten blocks from here and the situation might well be reversed. There is an ongoing battle between the town and a company that wants to deploy small cells here. I think it’s less a technology problem and more one of whose palms are getting greased. I suspect a similar situation pertains almost everywhere.
WiFi calling has been a great way to work around all the red-tape in telecommunications. Hopefully the new FCC will be a help in that direction too, but there is no guarantee of that. Some people suggest that if Sprint and T-Mobil are allowed to merge it will allow everyone to raise their prices. Furthermore if WiFi calling became commonplace I think there would be a downward pressure on prices since there would be less need for cell towers and the like in remote places.