What's your level, John?
Each of the nations has its benefits:
1. Chinese extra worker is a significant benefit. They also have a strong ranged infantry unit.
2. Greeks have a tank with extra dps, which is a significant benefit. (Their architectural bonus should be buffed, imo. But I believe it will be and wouldn't push people to change nations before global age is released.)
3. Japanese have a strong infantry unit and a treaty boost that would be quite useful for people who can't play as much.
So, I'm not in agreement on your rankings, since each player has unique needs. I'm tempted to switch to Greek, partly because people complain about them being underpowered.