cell phones, which one has the best service?

[cris]

Hi folks,
Much has been said about cell phones and accessibility.  My question is:
Which company has the best cell service in North America?  I heard a lot of
bad things about At&T and mixed views of Verizon.  Currently I have AT&T,
and was recommended to try Singular.  I like to hear privately from those
who have experience to share.  I have not signed any contracts yet.  My free
trial period with At&T is about to expire.  I want to decide soon if I
should keep it or try another service.  Please reply privately so as not to
cluttre the list.
Cheers,
Cris