What do you mean by "better off"?

America, Canada, Australia were all former British colonies/possessions, and they been "better off'" than say India, the nations in Africa formed by the British empire historically, is that sort of what you're alluding to?

Successes/failures of these places have a lot of factors in place, far more than just Britain's claim on them. Most books on colonization just cover the history of the discovery, the conquest, liberation, and lingering aftermath. I haven't read one that really pits the conquering nations against one another--at least not in regards to how better off their colonies were. Most of the comparisons circle on how fast, how big, and how quickly the empires were lost.

The idea of "better off" seem wholly like a revisionist attempt to soften of the horror that the natives of these places endured when Europe discovered them.

There are a number of books that compare the colonial empires of say the British and the French. "A Turn to Empire" by Jennifer Pitts comes immediately to mind.

I think you will find in reading on the subject that the treatment of indigenous peoples varies wildly; even within the Empire. For example, the French in New Caledonia annexed huge amounts of land from the native peoples and forced them into reservations; whereas in Tahiti they had a generally hands-off approach and recognized the right of local people to own property and so didn't seize much of it. The British Empire is much the same; the very forward racism of the 'white australia policy' or its equivalent in South Africa are hardly the actions of an enlightened colonial power.

Perhaps one of the biggest divides you will find; is how Empires treated their settler colonies vs their non settler colonies. After all, many of the colonies you mentioned in replying to someone else, Canada, US, Australia, New Zealand, South Africa; are all settler colonies in which the indigenous people would no doubt object to the idea that they were well treated. Those colonies definitely ended up, and were treated, much differently than the non settler colonies like India-Pakistan, Kenya, Congo, Indonesia, Samoa.