No European colonial power treated the Native American population the best. None not one. From the time Columbus came into the new world and to the time the European settlers(United States Of America) disrupted and move the Native Americans(North American Indians) and acquire there lands. please see (http://www.mahalo.com/answers/science-and-mathematics/what-was-the-reason-for-trail-of-tears) One first must look at the reason for Colonialism and also to understand the reason for it. This is a little definition

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Colonialism normally refers to a period of history from the 15th to the 20th century when people from Europe built colonies on other continents. The reasons for the practice of colonialism at this time include:

* The profits to be made.
* To expand the power of the metropole.
* To escape persecution in the metropole.
* To convert the indigenous population to the colonists' religion.
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information obtain from http://en.wikipedia.org/wiki/Colonial_power

History dictates that no European colonial powers treated any other race or indigenous people of any country or any continent better than each other. If you can prove to me that there was one colonial power that was more benevolent than the rest please let me know also bring the evidence to justify it. From the explanation above you do not need to be a professor to understand that any country or countries who set out to achieve this goal cannot do so unless they take over the foreign country.
Due to the migration of the Europeans to the Americas. The Native Americans population was nearly wiped because of War and violence, Exploitation,Massacres and diseases.

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Americans' eagerness to expand westward prompted a long series of Indian Wars and an Indian removal policy that stripped the native peoples of their land. The Louisiana Purchase of French-claimed territory under President Thomas Jefferson in 1803 almost doubled the nation's size. The War of 1812, declared against Britain over various grievances and fought to a draw, strengthened U.S. nationalism. A series of U.S. military incursions into Florida led Spain to cede it and other Gulf Coast territory in 1819.
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information quoted from http://en.wikipedia.org/wiki/United_states_of_america#History

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It is estimated, based on archaeological data and written records from European settlers, that from 8 to 112 million indigenous people lived in the Americas when the 1492 voyage of Christopher Columbus began a historical period of large-scale European interaction with the Americas. European contact with what they called the "New World" led to the European colonization of the Americas, with millions of emigrants (willing and unwilling) from the "Old World" eventually resettling in the Americas.

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information quoted from http://en.wikipedia.org/wiki/Population_history_of_American_indigenous_peoples

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While the population of Old World peoples in the Americas steadily grew in the centuries after Columbus, the population of the American indigenous peoples plummeted. This was caused mostly by their susceptibility to old world diseases (smallpox, influenza, bubonic plague and pneumonic plagues, etc.) which they had never been exposed to. Secondly, direct conflict and warfare with European colonizers and other Native American tribes caused populations to fall and societies to be disrupted. The extent (and, to a lesser extent, the causes) of this population decline have long been the subject of academic
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information quoted from http://en.wikipedia.org/wiki/Population_history_of_American_indigenous_peoples

You can also read the page on this link give you an idea of the Europeans early conquests of the Americas

Spain arguably did the best job. While France utilized various Native American tribes for their trade skills and didn't treat them like unintelligent savages like some British colonies did, their negative treatment was more backhanded and passive aggressive. They took advantage of them much the way modern American bosses do with illegal immigrants now - they worked for a lot less and were willing to trade things at unfair prices because the Native Americans were unaware they could get better deals.

Spain, however, was not as interested in taking their land from them or making profits from the trade of fur. They wanted to convert the Native Americans to Christianity, and while I suppose it could be argued that they treated them badly by only seeing them as potential converts and trying to force their beliefs upon them, they were certainly a step ahead of some British colonies who slaughtered them in their greed for land. Spanish missionaries took the time to live with the Native Americans and learn their language, something many of the other colonial powers had no interest in.

That's not to say, however, the British were all bad. The Iroquois favored them over French colonialists, who were trying to extend their hold over their colonies in Canada to include more of the south below it. This alliance was one more of convenience than one of mutual respect, but it just seems unfair to paint the British colonialists as the only ones who mistreated the Native Americans when it was truly across the board.