Very interesting thread! I would like to learn what sort of numbers folks would assign to these tiers.
For the sake of argument, assume a nakedciv with no UA, UB, UU is a base 100 points. Even forth tier civs have a weak UA, UB, UU, and with rare (but debatable) exceptions, all are better than nothing. Probably one of the three is at least mediocre, so at a minimum that is 1 point for two of them, and 2 points for the third, so 104 points.
On this scale, what kind of point rating do you intuitively think the the god tier civs rank? 150? 200? Does a god tier civ really out pace a naked civ significantly?
My guess is that, in the hands of any given player, the civ you start with ultimately only makes 10-20% difference in your final score. But I am quite curious about what others think of this theory!