As far as I am concerned it has the best signal, I travel quite a bit from major metros to the middle of nowhere and Verizon has worked the best for me. I used to have ATT TDMA and moved over to Verizon for less dropped calls, and more coverage. I have coworkers who use Sprint, Nextel, and Cingular, T-Mob and Verizon has worked the best. The others seem to work well, it just seems like I get better mountain top coverage, interior coverage, fewer dropped calls, and better middle of the nowhere coverage.
Just my opinion though.