what are the best domain extentions for business websites?
If you’re targeting a particular country, then a country-specific domain makes sense, and is used as a signal by search engines that you are targeting that area. (If you use a generic TLD, you can set geo-targeting in Webmaster Tools.) It also helps to indicate to potential customers that you are operating in their country.
Other than that, it’s really a matter of personal preference.
Normally, dot com domain extensions are widely used but if you want to do business in the specific country than you also use the extension of that particular country as well.