As I'd said weeks ago in another thread:
Rome: always weak, always shunted
Russia: generally ends up being weak
In two different games, I found myself donating a city that I didn't want to either of these civs just to keep things interesting - sort of a puppet government arrangement, I guess. Politically correct issues with it aside, it had a ring of creating "Manchukuo" to it on each occasion.
Americans generally smack in the middle of the pack
Japanese do just okay.
English generally moderate
Germans generally moderate-strong, and are more an irritating adversary than a difficult one.
India are pretty strong, but then they weaken on the way.
Zulus end up being very strong, and damn do you get pissed off if you end up at war with them.
The Aztecs are also a pain, although they do more with less - smaller empires, less tech, but very successful considering.
Chinese end up being very strong.
The French end up with half the map - always - but then their lack of culture seems to leave them weak to defections.
Since then, I've played several more games and found the Persians to be verydifficult and tenacious adversaries. The Babylonian cultural advantage doesn't seem to be so decisive, save and except in that they seem - as noted above - to be unconquerable. They don't win, but they don't lose either.
R.III