Here are overall ratings for US in 2004 www.jdpower.com/cc/telecom/jdpa_ratings/wireless/Find.jsp?s=6 for all major manufacturers.
However, if you are setting up new service, remember : Carrier first, phone second.
All the cool handset features in the world do you no good if the phone can't find a signal where YOU are.
Talk to folks who live, work, shop, go to school, etc in the very same places (not just the same county) where you do. What carrier gives them a good signal everywhere?