I would never want to move to another country, but if I absolutely had to, my musts would be a country that:
1. Was English Speaking
2. Wasn't prone to earthquakes, volcanic eruptions, or hurricanes
3. Had a similar culture/lifestyle
5. Free healthcare like the NHS
6. Not too hot or too cold
My list is pretty long and hard to come by, which is why I don't want to move. I think Britain is the best place to live. For that reason, I would probably choose a neighbouring isling like the Isle of White or something else close by.