Tough tough tough... I'm decently traveled, last count around ~45 countries visited and lived in 7 (spending at least 1+ years).
I get asked this question IRL often when people learn how much I've traveled and I always struggle to give a definitive answer. Outside of the standard metrics of cost of living, quality of life, healthcare, etc etc, a lot of what makes a country a "favorite" of mine is at a certain degree the people and connections I've made.
Ultimately, I tend to pick China overall as my favorite country to live, and to be more precise the Guangdong province area near Hong Kong and Macau. Living there in part from the 00s into the 2010s I got to witness an extreme explosion of growth across all sectors in the country. Architecture, history, culinary, and general vibes are all stand out above other places to me. The 24/7 active lifestyle and cyberpunk-esqe modern technology landscape speaks to my soul. The absolute biggest drawback and in part reason why I left were the Internet restrictions which touched a lot of aspects of how I made money online, it became infuriating because of poor connections to Google, AWS, payment services, etc I needed to interface with on a day-to-day basis. If I were to return, it would be solely to open a local and/or non-western targeted business.
Runners-up would probably be Taiwan or Japan.
For the misses I'm almost certain her choice is Turkiye, we spent 3 years there during COVID-era and she loved it. After spending a decade in China, she had enough... so I'm always trying to convince her to go back. Maybe one day.