Keller Williams scored highest on the customer-service rankings among home buyers, and Coldwell Banker ranked first among home sellers in the annual J.D Power and Associates 2009 Home Buyer/Seller study.

The study measures customer satisfaction with the largest national real estate companies. The most significant factor is the buyer/seller experience with the practitioner. Other factors include overall experience with the office and satisfaction with special services offered, like referrals to inspectors and lawyers. Home sellers also rate marketing.

The 2009 Home Buyer/Seller Study includes more than 3,100 evaluations from 2,801 respondents who bought or sold a home between April 2007 and June 2008.

Among the related findings:

• Home sellers report that, on average, 3.2 open houses were conducted for their property in 2009, compared with 4.5 in 2008.
• Approximately 64 percent of home sellers used a Web site listing to market their home in 2009, up from 61 percent in 2008.

Here are the home buyer rankings on a 1,000-point scale. (The home buyer average score was 791.)

• Keller Williams, 806
• Coldwell Banker, 801
• RE/MAX, 798
• Century 21, 795
• Prudential, 781
• ERA, 744
• GMAC, 731

Here are the home seller rankings on a 1,000-point scale. (The home seller average score was 786.)

• Coldwell Banker, 815
• Keller Williams, 801
• RE/MAX, 784
• Century 21, 770
• Prudential, 753

(NOTE: ERA and GMAC were included in the study but not ranked due to a small sample size.)

Source: J.D. Power and Associates (07/30/2009)