The Economist Intelligence Unit, among other things, ranks cities. It's offered a “Liveability Index” in the past but now enhances it with spatial characteristics for a new, improved “Spatially Adjusted Livability Index.” The seven spatial considerations: sprawl, green space, natural assets, culturual assetts, connectivity, isolation and pollution.
None of the top 10 are in the U.S.; they include: Hong Kong, Amsterdam, Paris and Toronto
None of the bottom 10 are in the U.S. either: they include: Tehran, Lusaka, Lagos and Karachi.
The top U.S. city, Washington DC was 14th.