Only one company seems to be well-liked by all of their customers:

Two other companies are liked fairly well by a majority of their customers:

 
TracFone: This is a "prepaid" cell phone, best for very occasional users. There is no epinions.com review of TracFone, but I found them discussed on a similar site and a majority of their customers were satisfied:
http://www.planetfeedback.com/ratings/Company/0,2489,100-162811-0,00.html

Three companies have customer service which is merely poor, but that still makes them better than most.  Most of their customers dislike them, but at least 1/3 are reasonably satisfied:

T-Mobile (formerly VoiceStream): Over 1/3 of their reviewers like them.  Too bad they don't accept customers in North Carolina:
http://www.epinions.com/elec-Comm-Mobileservice-All-VoiceStream_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des

AT&T: Back in 2001 quite a few of their customers were satisfied.  Now most people hate them.  Still, their average rating is better than average:
regular: http://www.epinions.com/elec-Comm-Mobileservice-All-AT_T_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des
prepaid: http://www.epinions.com/Motorola_AT_T_Prepaid_Free2Go_Wireless_Phone_Kit___Cell_Phone_V2397EPW

Most companies have customer service which is utterly hideous, and as a result the great majority of their customers hate them:

Verizon: Most people hate them, but a few are satisfied.  (This is painful for me to admit, because I'm a Verizon stockholder!):
http://www.epinions.com/elec-Comm-Mobileservice-All-Verizon_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des

Sprint: Most people hate them, but a few are satisfied.  People have told me that they seem to be getting worse:
http://www.epinions.com/elec-Comm-Mobileservice-All-Sprint_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des
[4/25/2003 - I now have Sprint, and I like them much better than Alltel or Cingular. YMMV. -Dave]

Cingular (formerly Bellsouth DCS, SW Bell, and one or two other companies):  I hated dealing with Bellsouth DCS when I had them, about 3 years ago, because their bills were always messed up and they were always trying to overcharge me.  About 1.5 years ago, I tried them again, as Cingular, but they couldn't even make their phone work within another State of the "region" (I had a regional plan), so I returned it.  28 out of the last 30 reviewers hate Cingular, but 2 of the last 6 like them.  Maybe they are improving?
http://www.epinions.com/elec-Comm-Mobileservice-All-Cingular_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des

Alltel: I had Alltel until a few weeks ago.  I truly hate them.  So do most other people:
http://www.epinions.com/elec-Comm-Mobileservice-All-Alltel_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des

Cellular One: Most people hate them, but a few are satisfied.  No coverage in Raleigh/Cary, anyhow:
http://www.epinions.com/elec-Comm-Mobileservice-All-Cellular_One_Customer_Service/display_~reviews/listype_~opb/pp_~1/sort_~date/sort_dir_~des

One company is worse than all the rest:

More user reviews here:
http://www.letstalk.com/reviews/reviewhome.htm
http://www.wirelessadvisor.com/waforums/join.cfm
-Dave Burton   9/25/2002