This is a big area of discussion - Native speaking teachers vs Non-Native Speaking teachers.
Around the world, it differs how much each is valued and it also differs in their own working conditions and career prospects.
Here are some articles highlighting these distinctions and more. See this huge discussion for a lot of insight from both parties! This poem by a teacher in Taiwan also lends voice to a lot of the content of this topic.
Here are some typical generalizations....
Here's another interesting article and take on this subject.