I'm trying to sort out the iPad carrier choices

Dear Folks,

I'm going to get an iPad Air to replace my iPad3 (Verizon version), but I can't figure out the diffferences between the four carrier plans. Here's what I care about:

1) Mobile hotspot. The reason I switched to Verizon from ATT when I got my iPad3 was because the data plan included hotspot capability at no extra charge. Do either Sprint or TMobile include this in their standard data plans for the iPad?

2) Out-of-US use. What I find I don't like about Verizon is that there's no real way to get international use on the month-to-month plan. ATT would let me buy data for Canada (albeit expensive). But with my Verizon iPad, the only option is to buy a SIM card. Do either Sprint or TMobile offer better out-of-country arrangements?

The two countries I care about are Canada and the UK.

Thanks!

Ctein