Melbourne is world's most livable city, Perth is the ninth.
Melbourne has claimed gold as the world's most livable city, but Sydney has lost its status as Australia's second most desirable destination ... to Adelaide, while Perth was ninth.
Melbourne edged out Austria's capital Vienna to claim the title of the best city in the world to live in for the second year running.
Vancouver, rated third, was one of three Canadian cities listed among the top destinations.
But it is Adelaide's ranking above Sydney that is likely to be the biggest local talking point, with the City of Churches ranked equal fifth, two places above Sydney.
Perth was ninth, sandwiched between Helsinki and Auckland. Last year the WA capital was joint eighth with the South Australian capital.
Economist Intelligence Unit survey editor Jon Copestake said that while Melbourne enjoyed top bragging rights, there was little separating the top Australian cities.
Four of the five Australian cities surveyed made it into the global top 10 and were separated by just 1.6 percentage points.
Brisbane was number 20.
"Australian cities continue to thrive in terms of liveability - not only do they benefit from the natural advantages of low population density, but they have continued to improve with some high profile infrastructure investments," Mr Copestake said.
"In Adelaide, projects completed in recent years under the Strategic Infrastructure Plan for South Australia have been enough to move the city above Sydney, whose score is unchanged (from 2011)."
The global livability survey is an annual list compiled by the EIU, initially as a test of whether human resource departments needed to pay a hardship allowance in expatriate relocation packages.
Melbourne's score of 97.5 per cent is close to the perfect score, with the city only losing points for climate, culture and petty crime.
Adelaide lost points on culture and environment but new infrastructure in the city catapulted it above Sydney.
The eastern harbour city scored well in health care, education and infrastructure but was regarded the least stable among the list of top 10 cities in a category that considers crime, the terror threat and the risk of civil unrest.
Mr Copestake said the impact of the Arab Spring and the euro zone crisis were significant factors in the 2012 global rankings.
At the other end of the scale, Bangladesh capital Dhaka was rated the least livable city of the 140 considered in the survey.
The Top Ten
2. Vienna, Austria.
3. Vancouver, Canada.
4. Toronto, Canada.
5. Calgary, Canada.
5. (equal) Adelaide.
8. Helsinki, Finland.
10. Auckland, New Zealand.
20. Brisbane.Source: The Economist Intelligence Unit's Global Liveability Survey 2012.