According to the Economist Intelligence Unit (EIU) in its latest survey, the answer is still Melbourne in Australia. My home city of London only rates 55th. What about your city?
The EIU’s “Liveability Ranking and Overview” assesses living conditions in 140 cities around the world. A rating of relative comfort for 30 indicators is assigned across five broad categories: stability; healthcare; culture and environment; education; and infrastructure. The survey gives an overall rating of 0-100, where 1 is intolerable and 100 is ideal.
More information here.