Melbourne has been named the world's third most liveable city, with Sydney 11th and Brisbane 25th.

The Victorian and NSW metropolises both fell slightly in Monocle magazine's 2014 rankings, while Brisbane was a debutant.

Copenhagen was named the world's most liveable city for the second year in a row followed by Tokyo, which finished fourth in 2013.

Falling from second last year, Melbourne won praise for recent public transport upgrades and its low crime rate - though Monocle's data gave it the highest murder rate on its index of 25 cities.

"Melbourne has proved that coffee and cricket aren't the only things it does well," it said.

Eleventh-placed Sydney - ninth in 2013 - was criticised for its public transport system and bar lock-out laws, introduced in parts of the city in early 2014 after the `one punch' death of teenager Thomas Kelly.

"Sydney remains Australia's face to the world - and a pretty one at that," Monocle said.

"Architectural breakthroughs such as the North Bondi Surf Life Saving Club and One Central Park are welcome additions."

Brisbane's role hosting November's G20 summit of world leaders propelled it into the spotlight.

"Arriving delegates will discover a sun-drenched destination with a flourishing start-up scene," Monocle said.

Monocle's rankings are the latest to try to corral disparate global cities into some sort of cohesive ranking system, with Sydney and Melbourne regularly featuring in the various top-10s.

But some of the data it used was questionable.

For example, the London-headquartered firm claims Sydney enjoys 2592 "sunshine hours", without offering a timeframe. Bureau of Meteorology data shows Sydney Airport recorded an average of 7.8 hours of sun per day in 2013 - or 2847 hours over the year.

Monocle also claims Sydney only has 42 book shops but directories show at least 22 in and around Glebe alone with many more across the city.

One of its judging criteria was also how many daily newspapers exist in each city (four in Sydney, three in Melbourne), disregarding the fact millions get their news online.

There was no room for London or New York in Monocle's rankings, with the magazine claiming London's police "can't always be trusted", without elaborating.

Retaining top spot on Monocle's index, Copenhagen was praised for its easy lifestyle and cosmopolitan feel.

Tokyo's food, arts and shopping ensured it secured second.