What type of impearlism was most brutal?

The direct rule is known to be the most brutal type of imperialism

The direct rule is known to be the most brutal type of imperialism - where a certain country is being ruled by foreign officials - therefore making it a colony. There is no self-rule for natives in here, and this is all for the sake of turning a large colony into a powerful empire. One notable brutality of direct rule in all of history happened when Belgian King Leopold II ruled the Belgian Congo. There were 10,000,000 locals that were killed during his tenure as a ruler. Other countries that practiced this method were France, Morocco and Vietnam.