Not to state the obvious, but nice is not the same thing as interesting, as seen with places like Vancouver, Zurich, Munich, Copenhagen - all cities that are routinely ranked at the top of those livability lists. Among those that don't make the grade: NY, L.A., Chicago, Hong Kong, and even London. They're all places where stuff actually happens. From the Financial Times:
Ricky Burdett, who founded the London School of Economics' Cities Programme, says: "These surveys always come up with a list where no one would want to live. One wants to live in places which are large and complex, where you don't know everyone and you don't always know what's going to happen next. Cities are places of opportunity but also of conflict, but where you can find safety in a crowd. We also have to acknowledge that these cities that come top of the polls also don't have any poor people."
In fact, it can often be exactly the juxtaposition of wealth and relative poverty that makes a city vibrant, the collision between the two worlds. Where parts of big cities have declined, through the collapse of industries or the fears about immigration that led to what urbanists have termed the "donut effect" (in which white populations flee to the suburbs, leaving minorities in the centres), there is space to be filled by artists and architects, by poorer immigrants arriving with a drive to make money and by the proliferation of food outlets, studios and galleries.