Hi Marjorie,
I myself do like to reassign affiliates to someone from their own country or region as much as I can. I think it's much easier for them to communicate in their own language and also they have a sponsor who knows the problems or the advantages of trying to earn a living in that country.
There's a huge difference in standards of living all over the world. If your sponsor lives in the same region or country they can relate to your needs much better.
I hope this helps!