I have never quit using AT&T (for long-distance service). I have never had a major problem, and when I have had problems, they were solved in a quick and timely manner. Bell South is my local provider since the breakup, and their service has been positive also.
LLS
I quit using AT&T in 2003 after they had committed what I consider to be the unforgivable sin in business. Depositing the check and claiming that I never paid my bill. At that point I dropped AT&T on both long distance and internet. AT&T has been a company with misplaced priorities, squandering resources on pandering to internal pressure groups via a large diversity directorate. The office politics within AT&T were getting to resemble Atlas Shrugged.