The CM Research Institute in Japan surveys 1500 members of the public every month to get their impression of the CMs currently airing. On May 22 they released a summary of the results for the last fiscal year. The most popular female CM actress was Hamasaki Ayumi. She was third most popular overall.
http://www.sanspo.com/geino/top/gt20...003052301.html
http://www.cmdb.co.jp/
If anyone is interested I'll post the all of the results later.