I don't care about tablets given by ISPs, since I can buy one if I need it. And I'd rather buy one which I need and which I can customize, not one which the carrier tries to give me with all kind of junk preinstalled (and which most probably comes with a locked bootloader, so no luck with installing other operating systems there). However getting a service you need is not always an option. Competition for ISPs means lower pirces for higher bandwidth, decent customer support, no contracts and no data caps.
And by the way, about Verizon - they are known to cause all kind of problems for tablets which "aren't authorized" (i.e. tablets with 3G/LTE connectivity). Just search for subjects like Nexus 7 not working on Verizon. I.e. if you get it from them - OK, but try connecting your own tablet - you can be out of luck. Such weirdness is unheard of in Europe.