I would say the Dutch because -after a couple or years of nagging, mainly about costs and "hidden influence"- they have modernized the Royal House Finances Act, they have modernized the Royal House Act itself, the new King keeps himself far from day-to-day politics and has an eye for PR by opening the palaces for the public, by inviting the men-from-the-street for a real lavish State Banquet for his 50th Birthday, by "controlling" the media via a so-called "media code" and the Royal Household Services seem one of the best run in the country, even subjecting the palace organization to ISO standards. The Dutch Court also tries to prevent "cliques" to request staff from departments, the armed forces, the judiciary, the diplomatic service, the banking sector, the hotel sector to work for the Court for a limited period. It prevents "little kingdoms" inside the organization. So all by all I think the Dutch is the best run one but it would have been a disgrace if that was not so: they are amongst the most expensive Households overall.