There seems to be an inverse (I guess pretty unsurprising) relationship between being decent and being cheap. Unfortunately it doesn't seem to be 1 to 1. But almost everywhere attractive in Europe is now very expensive. Cities like Berlin, or even Lisbon, are pricing themselves out of the race. The US doesn't seem to be worth it anymore overall for Europeans.
So what I have managed to find on paper is Slovenia which supposedly has low taxes and decent quality of life but is tiny, relatively inaccessible and still a bit expensive. Another option seems to be something like a second tier city of a bigger country. Like Porto, Valencia and Montpellier and maybe Hamburg.
What sort of surprises me is that I haven't really been able to find any, at least not European, city which seem to want to attract people based on quality of life. All these "next silicon valley" type statements always only talks about things that largely doesn't matter. Not how to live there for 1 week, 1 month or 1 year. Have you noticed any city, or even region, doing better in this regard?