Why there is no harmless imperial model

Which empire did the least damage to its colonies, or perhaps improved them?

None provides a harmless model; all of the empires discussed caused damage and cannot be reduced to a simple improvement ranking.

The preceding logistics comparison does not become a moral league table. Every imperial system discussed caused damage, even where particular territories or relationships produced more complicated local reactions. The brief Goa example adds complexity without establishing that Portuguese rule was benign. Efficient routes, profitable factories, and durable infrastructure describe how an empire worked; they do not show that its domination was justified or beneficial.