A city in the midwest US would provide your best long term balance of noted factors. Low cost of living, high quality of life, with none of the economic distortion that occurs on both booming coasts. You get four seasons with a nice balance that allows for comfortable summers with long days plus real winters that provide natural beauty and life-balance.
With global warming, the midwest US cities near the Great Lakes (Chicago, Cleveland, Columbus, Cincinnati, Indianapolis) are poised for growth. Some of the smaller cities in this region are still recovering from the rust belt days, but they will boom in decades to come. While the southwest and southeast choke in drought and massive heatwaves, also struggling with the weight of their own economic excesses, the midwest will see an influx driven by less-heated economies, readily available fresh water, reasonably-priced labor, moderate weather and moderate, livable scale of its cities.
This shift is coming.