Then EU > US. In the EU most people have a shot at this, with free education and possibilities. In the US your chances are mostly tied to your parents' status.
> It feels like there's very little social mobility in Europe compared to the US
Maybe from middle class -> very rich. But from poor -> middle class Europe is absolutely better.
Not with very low salaries and even more unaffordable real estate than in the US. Yes jumping from “lower” to “middle” class seems to be generally easier in Europe but the likelihood that you’ll just get stuck there is much higher.
> In the US your chances are mostly tied to your parents' status
Inherited wealth is as if not more important in Europe. Because while yes free education etc. give you more possibilities the ceiling of how high can you go up on your own is also generally much lower.
In the us they might have more money (to then spend on healrhcare etc)
Which is “better”?
If you’re below the average (income/wealth wise) and have other disadvantages you might certainly be better off in Europe. Otherwise (inherited wealth aside) US might be a better place to be depending on your personal preferences and priorities.
The transit is trash anywhere that you can actually afford to own property. The healthcare outcomes you mentioned are going to need a citation because the middle class in the US generally has OK insurance.
For happiness, that’s vague and will need a citation. Putting the entire US on a comparison with individual EU countries is dumb, but that’s how it’s sliced in https://en.wikipedia.org/wiki/World_Happiness_Report where the US is beat by many EU countries and beats others (e.g. Spain and Italy).
> Which is “better”?
Probably the one with the most immigration.
This comparison only works at birth, or maybe up to teens. We are, most likely, working professionals here. With a degree and fairly established position. Becoming a millionaire is still a monumental task. However at this baseline US is much easier.
Is your goal really “become a millionaire”? Not “have the ability to see the world” or “live in a nice house with kids an a dog”, just “have 7 figure on a spreadsheet of what I have managed to accumulate”
7 figure on a spreadsheet enables a lot.
An unregistered savings account in one of Canadian banks (just a point of reference, not sure if US has better) currently offers 4% yearly. That's 40k a year off the million. Enough to retire with kids in a LCOL country or travel year round as a nomad with a base in LCOL country.
Build a little bit more wealth and all those LCOL options turn into MCOL. E.g. northern Italy.
All while just being a working professional. It'd be unheard of in Europe to have this kind of options after just a couple years of work.