I am going to Disneyworld and own a VZ Galaxy S3 and a AT&T version. Which has the best signal strength at Disneyworld. I don't want to carry but one phone.
Check www.sensorly.com for user contributed maps. Most of Disney had Verizon 4G on my Thunderbolt and I did some mapping there. I think my wife's AT&T phone had good signal except inside a few exhibits. I think either would be okay.