That's a big life decision.
I've lived in Europe my whole life, but I have a lot of friends and relatives in the US. I've also lived in 3 different European countries, and of course I know people from just about all the Western European nations.
There's a lot got you to think about. This is only a small part, off the top of my head:
- If you're American, you pay tax worldwide. Most countries have higher tax than the US, so you just pay their tax. Switzerland is different. I lived there, it's a pain as an American to even get a bank account. And you'll have to file a return. A friend of mine is half American and is an accountant. It's annoying for him as well.
- Languages. Which do you speak? Most Northern European countries have significant numbers of companies where they speak English. That's not to say you can't learn the language, English is a Germanic language, so not a million miles off German, Dutch, Danish, Swedish, etc. Yet you're not going to understand it getting off the plane.
- Social. Are you coming by yourself or are you married? Got kids? It's hard to find documentation for this, but the way one socialises depends a lot on which country you're in, whether you're in the countryside or the city, and whether you have kids or are single. Anecdotally I'd also say some of the Germanic nations have hard-to-penetrate social circles. It's not that they don't like you, they already have their friends and haven't needed to make new ones since college.
- Culture shock. I guess you actually want that. But remember you can drop a guy from New York in LA and they will not have a problem at all. Take a guy from Edinburgh to Rome, and they are now a tourist. The plus side is it takes a two hour flight to see something completely different, with different looking people, weather, history, and so on.
- Visa. This is going to depend a lot of the specific country.
Anyway I'm sure you'll have questions.