Mainly the US has many benefits:
- Much, much higher salaries - like 2-3x higher than Western Europe _before_ income tax!
- Much larger houses for the price. i.e. you can have a big house with room for hobbies or children rather than just a small flat.
- Lower prices on a lot of fixed-price goods - cars, electronics, fuel, electricity, natural gas, etc.
- Lower income and sales tax so you can save for a property and retirement. This is really tough in Europe, the sort of Tech FIRE culture doesn't exist due to that - wealth is primarily inherited.
The downsides are:
- It's a necessity to drive, but at least outside the big cities it's a lot easier than Europe overall (big, wide, straight roads and automatic cars).
- Healthcare is tied to your employer so it can be incredibly risky when moving as an immigrant since until you get a Green Card, you are tied to the one employer (good luck negotiating a raise!). Note that in most Tech companies, the health insurance gives you better coverage than public systems in Europe (e.g. covering dentistry and annual checkups).
- Less stability in employment - at-will employment, lower unemployment payments (except vs. the UK), no trade unions in Tech.
- Safety in some areas wrt. gun crime, etc. - you have to choose where you live and work very carefully.
- Backwards in some technology (online payments, card payments, digitisation of government services vs. the UK and Scandinavia for example).
A main decision point would be if you have kids. Europe is great to move to if you've already saved a lot in the US, can move to Europe and buy a house outright, get permanent residency and then have children and benefit from better paternal leave and even universal child benefit payments (Kindergeld/Barnbidrag, etc.)
Whereas if you are child-free, and don't already have enough savings to buy property, it's going to be harder to achieve that in Europe IMO.