It depends on what you think of as QoL. The population of the planet has approximately doubled in the past 50 years, so if QoL requires stable population density then not many places are going to meet that requirement.

But when I was a kid the neighbors didn’t have indoor plumbing, and that was just normal back then. I think ~1940 was the point in the US where about half the houses in the US had an indoor bathroom with hot and cold running water. In the 1950s, almost nobody had air conditioning and now it is almost universal in warm climates. Since the mid 1980s, the infant mortality rate in the US has halved. Although the murder rate is higher now than a decade ago, it’s lower than it was in the 1990s.

I put over a decade of work into my big move and it was worth it for me. But my strategy was to save up enough money that I could live in my new country without working. That gives me the flexibility to move to a new place if my dream destination had not lived up to my expectations. If plan A had not worked out all my work would not have been for nothing.

If London is your dream, you might be able to get a student visa and earn a degree in some field that is in demand. It would take time and money but at least if it didn’t lead to a job in London it might advance your career in general

I’m in France; I don’t know about the other countries you list.

If your disability compensation is more than about 1300 euros per month, and is expected to be stable into the future, you could probably get a non-working visa here. If the stability is in question, it might be wise to save up a year’s worth (12X1300) so that you can prove financial stability outside of the payments. 1300 euros per month won’t go far in major cities but you could make do on that in less-tight cities, probably with roommates. Or a small apartment in a rural area.

It is a one-year renewable residence permit. After five years of renewing you are eligible to apply for a ten-year residence permit that allows you to work.

If you want to work here, it is best to get a degree here, or work for a multi-national company in the US that would then let you transfer to France.

Most universities require a B2 level of French, some C1. Cost to foreigners depends on the school and how long you have been resident in France, but most are nowhere near the cost of US universities.

No, about A2 when I moved. I’m more like B1 progressing towards B2 now. I moved on my own.

Yes, I moved to Paris from the US almost 2 years ago. Best life decision ever.

If you are making 6-8K USD per month as a self-employed person, you won’t need to worry about affording housing in any of the places that you mention.

I have found that in my own life, happiness requires some level of stability, especially financial stability. I was never comfortable with the lack of a robust social safety net in the US. But I don’t see the connection between stability and flexibility. I have no problem with making last-minute plans, for example, and I think openness to other people is important. Maybe I’m not understanding you, but you seem to be making a connection between two things that don’t seem obviously connected to me.

I visited different places until I found one that suited my personality and values. It pretty quickly felt like home upon moving and getting settled.

But I don’t have strong ties to the place that I came from. If the main reason you don’t want to stay in NZ is that you miss your friends and family, that is going to follow you if you go anywhere except back home.

If it is more that you miss having social ties, and you didn’t find them in NZ, that’s something that could be overcome in a new place.