VIENNA (REUTERS/AFP) - Vienna, Austria's elegant capital on the Danube river, has again been commended as offering the best quality of life of any city in the world.

Baghdad, once more, was deemed the worst to live in.

The consulting firm Mercer said German and Swiss cities also performed well in its annual quality of living rankings. Zurich, Munich, Duesseldorf and Frankfurt remained in the top 10.

Hot on Vienna's heels were Zurich in Switzerland and Auckland, New Zealand.

The rest of the top 10 were Munich, Vancouver, Dusseldorf, Frankfurt, Geneva, Copenhagen and Sydney, according to the ranking of 230 cities.

Mercer's survey helps companies and organisations determine compensation and hardship allowances for international staff.

It uses dozens of criteria such as political stability, health care, education, crime, recreation and transport.

With a population of 1.7 million, Vienna topped the survey for the sixth year in a row, boasting a vibrant cultural scene alongside comprehensive health care and moderate housing costs.

The Austrian capital's extensive public transport system costs just one euro (S$1.52) a day for an annual pass.

Its Habsburg-era coffee houses, architecture, palaces, operas and other cultural institutions make it a prime tourist destination.

Europe has seven of the world's top 10 cities in the 2015 survey.

Tokyo was placed at 44th, Hong Kong at 70th, Seoul at 72nd and Taipei at 83rd, while Shanghai was listed at 101st and Beijing at 118th.

The top Middle Eastern city was Dubai, at 74th, followed by Abu Dhabi at 77th.

Baghdad, the Iraqi capital, was again ranked lowest in the world and was preceded by Bangui (Central African Republic), Port-au-Prince (Haiti), Khartoum (Sudan) and N'Djamena, the capital of Chad.

Waves of sectarian violence have swept through Baghdad since the American-led invasion in 2003.