If your requirement is the EU (and not merely Europe) ... I've heard the best things about the Nordic countries (especially Sweden) and Cyprus

Switzerland isn't a member of the EU (https://www.schengenvisainfo.com/countries-in-europe/eu-coun...) - but the folks I' know who've lived there liked it (minus cost of living)

I've also heard good things about Iceland - but, again, they're not an EU member nation