Do we submit creative or unique contents to article directories?

I have notice that if I submit unique, unpublished article to article directories then the article tends to rank improved in the search results and has better syndication rate as it is more visible to possible syndicates. And also people who come to my niche sites through the article resource box don’t have to read the similar article again on my website. The profit of submitting unique content for me seems to well outweigh the little additional cost. But I suppose that you can also do quite well reusing the content of your website.