T-mobile rated pretty well in Consumer Reports' last review. Sprint didn't, though. T-Mobile has a $40 / 1000 anytime minutes plan (includes long distance and out of area, but there are no off-peak minutes).
It depends where you're using the phone. In general, Verizon has the best coverage, especially in New England, but their coverage is a bit spotty in some rural areas in the Southeast....Sprint often works better there. As far as I could tell, Sprint works everywhere on I-95, from the New Hampshire / Massachusetts border through the bottom of Florida.