Oh, exciting! 🤩
Some ideas going somewhat from the south to the north.
Southern Europe: For climate change reasons I would exclude the most southern parts of Europe: the south of France and Italy and basically all of Spain, I believe. Probably also Portugal. Heat waves of 40 degrees and lack of water are already standard, these countries are not used to it as Australia might be, and it's only going to get worse, the land is drying out and fires are getting more common.
Know that some climate is regional, e.g. Lyon in France gets quite hot in summer, but go a bit further in any direction and you're ok. Go up into the mountains and it gets colder anywhere.
Being Australian, YMMV on climate perception...
Personally I love Croatia and the Balcan but I'm not knowledgeable about finances there.
Romania might be interesting, beautiful country and great people, maybe similar dynamics in the neighbouring countries.
Germany should be good tax and health ensurance wise, people might seem generally less approachable than in southern Europe but are good, think English personality wise, language is in the same group as English, so is Dutch.
Switzerland is beautiful with a truly outstanding infrastructure (and has three distinct language regions, German, French and Italian) but with Luxembourg and Lichtenstein the most expensive European countries to live in.
Anywhere north of the northern German border expect long, dark and wet winters, already somewhat the case at the hight of the middle of Germany.
I would consider financial aspects but look further to find a spot where you will be happy. Give us some pointers about what you appreciate and value (urban/rural, hobbies, necessary infrastructure for your business, travelling plans, personalities you prefer...) and maybe what your budget will be... Which regions in Europe have you already visited and what were your impressions?
I'm curious to read more about your journey!