The rules say you can have more than one builder on a road or in a city, so what happens when a city is completed and it has a follower and builder of one person and a big follower and builder of another person? Does the builder count as a follower or do you only count the other normal followers?
Builders (and Pigs) are not followers and are not counted when calculating a majority.
In your case, the city would be scored for the owner of the big follower.
Originally, builders and pigs were followers but this was changed a while back. Rio Grande Games adopted this rule upon the release of the Big Box Edition.