Double post, sorry!
Another way of saying what I did is that you can divide civs up into categories of importance.
Primary, Secondary, Tertiary, Quaternary say.
How this is done is inherently arbitrary of course...
The games produced by Firaxis should have mostly Primary, with some Secondary as well.
So Primary includes China, India, Germany, Aztec (representing at least one native Americas civ), etc...
Secondary would be Portugal, Khmer, Iroquois, Korea, etc...
Tertiary is those civs which most people here are keen on, which modders will be quick to make, Poland, Australia, Israel, Scotland, etc...
Quaternary are those who are too obscure to have many advocates, Tonga, Tarascan, Kongo, Ashanti, etc...