Personally, I would never move to the US. I do not like the culture, or what it has to offer. However, if I had a choice to work with anyone on a business venture, I would pick an American in a heartbeat. Their work ethic is second to none. I would also consider raising money in the US, as their investors are much more knowledge and much easier to work with than, say Europeans. So, it remains in many ways a land of opportunity in the modern world. If you'd like to take a shot and try to become a multi-millionaire, and don't mind putting up with huge wealth inequality, no safety net and basically winner-gets all mentality, I would strongly consider going there.
I would not be picking a country if that were my situation, based on taxes. You can move to any country on the planet and hire a good accountant who will optimise your taxes and chances are your effective tax rate will end up in the 20-40% range. However, your base salary could vary enormously depending on where you work. The same financial analyst working for exactly the same bank could easily have a salary thats 50% more in New York, than Paris, or Frankfurt.
Some banks will not want to accept US citizens/Green card holders as customers due to FACTA. US expects that every foreign bank report every bank account held by an American to IRS. Some banks chose not to get involved in this. From my experience, its a bit random which banks will and will not work with Americans. We are talking about Retail banking here, so for them its a simple cost calculation (# of Americans opening bank accounts vs. cost of compliance and potential liabilities). But, it is something to consider, along with the fact that you will always have to report your worldwide income to IRS and in some cases pay tax in the US even if you choose to emigrate in the future. Thats not a liability I would want to have, or subject my children to in the future.