I have both. I have a 15gb plan with AT&T and 2 phones and a mobile hotspot BUT I'm also including the cost of the phone in monthly installments and pay $206/month.
For a vast majority of the time, the mobile hotspot is off because we have an unlimited data plan for a Verizon hotspot. I bought this from a reseller ($900 one-time fee) and then my monthly bill is $70-80/month.
As for coverage- I've found they're about equal. AT&T works better in some places and Verizon works better in others. Some place, neither works at all.
(Edited to correct typo in "one-time" fee.)