However, measuring them against competing insurance brokerage firms, Greenwich said that in a series of categories—among them claims coordination and customer service—the smaller brokers outshined the three major brokerage firms.

The winners of this year's excellence award were rated “excellent” in customer satisfaction by at least 50 percent of their clients, noted David Fox, Greenwich Associates consultant.

“In comparison, none of the major brokers are rated as 'excellent' in customer satisfaction by even 40 percent of their clients, and certain firms fall below 30 percent,” Mr. Fox said in a statement.

The major differentiator between the three major brokers and the middle-market brokers, according to the survey, is devotion to client service.

“Even if the overall capabilities of these firms fall short of those offered by the major nationals, corporate risk managers say the smaller firms are able to marshal the resources needed to meet their needs because their organizations are built on client-centric models,” said Mr. Fox.

What large brokers offer is international capability that middle-market brokers lack and can't duplicate.

The advantage for middle-market brokers, the survey found, is the “day-to-day basics of managing coverage and claims for clients. The survey said risk managers rate middle-market brokers as being 50 percent more effective than large firms in claims coordination.

“Risk managers see smaller brokers are more interested in being partners, as opposed to providers,” said Mr. Fox.

When it comes to assessing the three major brokers, Greenwich said in terms of overall satisfaction, both MMC and Willis stood at over 30 percent of those surveyed scoring the firms as “excellent” and showed improvement over the prior year.

Aon, on the other hand, “ranked well behind the pack,” Greenwich said, and saw its share of “excellent” ratings decline, going from 39 percent in 2009 to 29 percent in 2010.

Mr. Fox said the survey results indicate that the major national brokers are relying upon historic relationships and international capability to maintain their current market levels. However, the increasing sophistication of risk managers has them reaching out for a greater balance between international capabilities and client service for the day-to-day things.

“The challenge to the major U.S. brokers is to respond to these demands by stepping up the quality of service they deliver to large companies in the United States,” said Mr. Fox.