Best connectivity overseas - Sprint
AT&T has the globe covered, with 220 countries served. So it's nice to know I'll have coverage should I find myself in Afghanistan (well, in theory). Canada starts at $0.79 per minute, or $0.59/min. if you have the World Traveler package. Mexico is $0.99, or $0.59 with World Traveler. AT&T also serves more than 140 cruise ships.
Verizon offers coverage in 40 nations, with rates ranging from $0.69 per minute (including Canada) to $2.89 per minute, should you be visiting Bangladesh. There is a second option, the Verizon Global Phone, that works in 220 nations as well as more than 100 cruise ships.
You need a separate phone because Verizon uses CDMA, which is not that widely used around the world. GSM is the most popular standard. Hence, why AT&T doesn't need a separate phone. The good news is Verizon's Global Phone selection is respectable, including Droids and Blackberrys.
Sprint offers global roaming, starting at $0.59 for Canada, $1.69 for Mexico and up to $4.99 for remote nations. No special plan or phone is needed, although some feature phones don't work internationally. It has cruise ship support and offers 4G coverage in Taiwan and Jamaica, mon.
More than 40 T-Mobile phones are certified to work outside the U.S. T-Mobile's Canadian coverage is $0.69 per minute, Mexico is $1.49 per minute, and rates top out at $4.99 in places like Kazakhstan. Veddy nice.