Among the top-four nationwide carriers in the United States, AT&T has managed the lowest ratio of Better Business Bureau complaints to customers over the past three years. Earlier this month, the BBB published data collected between August 2008 and July 2011 for the eight biggest wireless carriers in the U.S. The firm then measured total complaints for each carrier against its approximate total subscriber count according to the CTIA as of July to determine each carrier’s “complaint ratio.” Read on for more.