Is the city-dweller preferred over the Bedouin in marriage according to Islamic law, and has Islam stipulated that the city-dweller is more knowledgeable than the Bedouin?

The correct standard for prioritizing marriage proposals is religion and character. So, marry those whose character and religion you approve of, for if you do not, there will be tribulation and widespread corruption. This does not preclude considering other matters that achieve compatibility of temperaments and facilitate understanding between the spouses. The Sharia did not generalize that a city-dweller is more knowledgeable than a Bedouin; rather, it made piety the criterion for preference among people.