Of course it varies from city to city, but indicative numbers are along the lines of plus 3

, minus 11

. The ratio is usually about 1:3 to 1:4

to

, with the science being subtracted. I'm running at about 70% science - which I think has an effect. Perhaps later on when the cities are all huge (they're all around 15 to 25 at the moment) the +15%

will indeed outweigh the lost flat commerce, but that's not the case yet (late industrial).
Perhaps, just as an idea, the Bazaar and Market could be modified to make them more similar to the Shopping District, so the whole building line takes a consistent approach: e.g. this whole building line is purely +X%

rather than adding commerce to start with and then changing to a gold bonus. Is the +1

from incest considered important? I usually find that

isn't that hard to deal with.
Cheers. A.