<font color="blue"> now part of Verizon which uses GSM </font>
Verizon is CDMA. As to which is better, it depends on your area. Both are good technologies. Never make a cellular decision based on GSM vs. CDMA! Find out who is better where YOU want to use a phone. There is more difference caused by local engineering practices and marketing decisions than there is between the technologies.
As for Sprint and coverage - if the general public could see how very little coverage they actually provide (I mean, not roaming on someone else) compared to their competitors, they'd be laughed out of town. They are the BEST at marketing in the business, and nobody else is even close. They're selling like they're a Major League player, when actually from a coverage standpoint they are Little League.
How would I know? 22 years in the business this month.