It's like this, people prefer Verizon because they have the most coverage, and people prefer AT&T for the best phones and coverage as well. That being said as a result the prices are very high and are twice than what I am paying on T-mobile for comparable services (I get coverage wherever I'm at so I don't care).
CDMA- phones are restricted only to the carrier and the data is programmed onto them. Its also not as easy to switch phones. CDMA albeit with better signal strength, it has poorer capacity and slower speeds than GSM. For example CDMA EvDO speeds can only top out at 3.5mbps (sprint only maxes out at 768kbps due to its capacity issues and averages much lower).
GSM-uses SIM cards, has better signal quality, capacity and faster speeds.
CDMA- phones are restricted only to the carrier and the data is programmed onto them. Its also not as easy to switch phones. CDMA albeit with better signal strength, it has poorer capacity and slower speeds than GSM. For example CDMA EvDO speeds can only top out at 3.5mbps (sprint only maxes out at 768kbps due to its capacity issues and averages much lower).
GSM-uses SIM cards, has better signal quality, capacity and faster speeds.