U.S consumers are more satisfied with Yahoo! than with Google, Ask.com, MSN or AOL, according to a new measurement study by the American Customer Satisfaction Index.

However, the real situation for search engines is much more complex than that.

"Even more important than Yahoo!'s first lead over Google is the trend of their scores moving in opposite directions. We may see a real turnaround for Yahoo! in the next year." said Larry Freed, president/CEO of ForeSee, the sponsor of the ACSI report.

For those portals, the most visited subdomains define the most popular offerings. According to a Quantcast study in December 2006, the most popular application for AOL was Instant messaging. For MSN and Yahoo!, it was e-mail. If we define a portal as a gateway to other destination, then Google is the one. Its most popular subdomain is the specialized images search.

Thus, search, communication and content differentiate the top four portals. It is important for marketers to choose the best portal in order to reach the customer group they want to reach, or maybe a mix of them.

"For most brand-oriented campaigns, a mix of portal placements and focused ad network buys can offer the greatest reach—with the caveat that a good share of the audience might be duplicated across the portal-network combination," eMarketer senior analyst David Hallerman stated in an eMarketer report.