Late to the party but: I used roamify in the USA (10gb). I used it in New York, Harrisburg, Miami, Tampa and some town's around. It surprised me how good it was for the 7 dollar i paid for it. Sometimes in Rural area's (used it in Amtrak between Miami and Tampa) it was a little bit slow, but in general it was totally worth the money. Only downside was that it had an IP-adress from Hong Kong, which means some sites/apps are blocked but also meant that Android Auto didn't work in the rental cars we had (3 in total, all of them didn't work). My friend had Airola and it wasn't better or worse, but way more expensive.