The  annual roundup of the global cities with the best quality of life is here, and Zurich once again comes out on top. Here's a look at the top 10 cities.

Rationale behind the ranking

New York, London and Paris are internationally renowned cities but consultants at Mercer Consulting have picked Zurich, Switzerland, as the best place to live in the company's annual survey.

Consultants rated each city on a variety of factors including the level of traffic congestion, air quality and personal safety reported by expatriates living in more than 600 cities worldwide. In the top 25, U.S. cities such as San Francisco, Boston and Chicago were all edged out by Geneva, Switzerland, Vancouver, Canada, and Auckland, New Zealand. The highest-scoring U.S. city is Honolulu, which came in at No. 28.

Still, Mercer acknowledges that cities with a high quality of life are not necessarily the most exciting. "There are a lot of 'sleepy' towns that got high ratings," said Rebecca Powers, a principal consultant in human capital for the company. "But if you were to judge them on something like nightlife, there are some that probably wouldn't have rated as high."

The rankings are based on a point scoring index, with Zurich scoring 108 and Baghdad scoring 13.5. Cities are compared to New York as the base city, with an index score of 100. The quality-of-living survey covers 215 cities and is conducted to help governments and major companies place employees on international assignments. The survey also identifies those cities with the highest personal safety ranking based on internal stability, crime, effectiveness of law enforcement and relationships with other countries.

By Carl Winfield, BusinessWeek

* The World Factbook