Somewhat subjective, I'm going mostly by military power, the ability to project, and economic power.
1. USA- Defense budget greater than the next nine competitors.
2. China- Economy improving. Army is large, though uneven in levels of training. Navy is somewhat weak, not even independent.
3. Russia - Tossup with them being #2. Army large, but not well trained. Lots of equipment, but most of it is old and poor maintence. Lot's of nukes. However, unable to really project military power beyond its borders, though it can economically pressure its neighbors.
4. UK- Good economy. Well trained and mobile and deployable army. Sierra Leone is the best example of that. Also, the navy is still decent and able to project power with those Harrier carries. Plus I heard Blair was ordering that new bigger carriers be ordered.
5. France - Decent army. Has the DeGaulle carrier, so able to project some power.
6. Japan: Good land army, decent navy. Limit's its military, not easily deployable abroad, which is why I am lowering their rating. #2 economy of the world.
7. India: Massive land army. Nuclear power. Good navy, has I think two old British aircraft carriers.
8. Israel: Economy good, especially the high-tech sector. Very good Air Force, good land army. Navy is somewhat small, but dependable (frigates, gunboats, and a few German submarines I believe). Nuclear power, with missiles capable of hitting anything in the MidEast. Limited by their small population and the need to mobilize their entire population in case of full scale war.
9. Germany: It has been referred to as an Economic Giant, but a political mouse, for obvious reasons. Trouble integrating East Germany inside.
10. Iran: But far down the list compared to the others. Weak economy. Military ok, but only fought Iraq to a standoff. Only on the list due to increases in missile and nuclear technology.
As for me, I would live in UK as my number two choice. Everyone would have a jolly accent, and I could keep my language.