Welcome to the Q&A Forum

If one were better than the other (and I'm not sure of any research comparing the two), then I would guess at .cn, since that's as top level as you can get with it (I know their both top level but that was the original).

Hey Paul, there is another good one out of Calgary, Alberta. They are called Alberta SEO. https://www.seoalberta.net I've used them in the past for link building campaigns and they always do a great job. Links are always clean.