UK->BC. Gave me a lifestyle and standard of living I could never have had where I grew up. Improvements of weather (long hot summers, short, real, winters, way less rain), property (larger & cheaper), geography (the mountains, valleys, deserts, lakes, and forests here are stunning), employment (my salary is about twice as high as it would be).

Contrast to your list, Australia I never really thought about and just assume I'd die of skin cancer while screaming about the poisonous spider in my shoe, New Zealand is, as I understand it, like moving to Britain in the 1970s except with a modern cost, USA I like both not being shot and also not then being billed for the bullet removal, and western EU definitely options I considered, but ultimately while my French is good it's not fluent, and while I can read Spanish reasonably well I have no experience speaking it, and I'd feel awkward moving to a country where I couldn't communicate well.