In the mortgage market, 74% of building society customers say they are either extremely or very satisfied with the service they receive, compared with 63% of customers at other providers.
Meanwhile, 67% of savers with building societies also say they are either extremely or very satisfied, compared with 53% at other savings providers.
The research shows that societies are perceived by their customers as outperforming banks when it comes to treating customers fairly, providing better value for money and being trusted to give good advice.
The research was conducted in October 2008, at the height of the instability in the financial markets.
Adrian Coles, director-general of the BSA, said: “For the second year running, this research shows that mutuals beat banks in every aspect of customer service. Building societies pride themselves in offering the best service to their customers. As mutual organisations, they do not have shareholders to please so they are account- able only to their members.
“With household incomes being squeezed, consumers are looking for good value, and this is an area in which societies excel.”
He added: “Recent falls in interest rates will make it even more important for consumers to seek out the best deals on savings and mortgages.”