Based on sales anyway, not necessarily taste.
From the Los Angeles Times:
Folgers holds an average 15.6 percent share of the U.S. market. J.M. Smucker Co., the company that manufactures Folgers, reported that profits for its U.S. coffee retail segment was up 16% to $19.6 million.
If you compare those numbers to the amount of Starbucks being sold, at a 3.3% share of the market, people purchase Folgers five times as much as they do Starbucks beans.