I have personally live in Belgium, Germany, UK, Italy and Spain. I also visited many times France and a least once The Netherlands, Luxemburg, Portugal, Greece, Austria, Switzerland, Czech Rep, Hungary, Norway, Latvia, Andora... By lived I mean having stayed there at least a few months continuously, speak the language and have lived in local families, so as to know the people and the culture well.
I can say quite easily that Italy is the best everything included (climate, food, people, culture, history, nature, language...). France and UK come second. Spain has beautiful landscapes, but I don't like the food especially. Many Northern country are liveable but too cold and boring (except Norway that is quite beautiful).
Having growned up in Belgium, I don't understand why so many of you have chosen the Benelux. My Japanese wife however like Belgium very much (chocolate, waffles, Brugge, castles...). Holland in the Netherlands is slightly better than the rest - especially Amsterdam. But my top 3 is definetely Italy, UK and France.