did slavery had a greater impact on the west indies or west Africa?

Answer 1

Clearly the West Indies. Most of the present day population there came from the original West Africans imported as slaves.
The people lost to West Africa would be replaced by the ever growing population in that area of the world.

The West Indies had been populated by the Carib Indians who were almost completely replaced by the African people. Most - perhaps 90% - of the native West Indians died from newly introduced European disease such as small pox. Replacing the indigenous population with an entirely new demographic is a greater impact than the removal of a minority of the people as occurred in West Africa.

Answer 2

I would say west Africa; because due to deaths in transit, they lost more people than the West Indies gained.

***thumbs up to spreedog. I just wanted to point out that it is a matter of perspective.