Well, I was INCREDIBLY lucky to be able to come to Oxford to work. My boss is a very famous man in my area of research, and I’ve met many other interesting people through him. I think Cambridge is prettier than Oxford, so maybe there :p
But if I had to work anywhere, it’s less about which country, and more about the institution. I would like to work for an institute called The Max Planck Institute. They’re a research only group, who do very challenging and interesting work, and have the time and money to invest in new ideas. That would be my dream job (well, being a director of a Max Planck would be my dream job).