It is a great idea to write your own articles and stick them on your site. It is not such a good idea to send the EXACT SAME articles to other sites for the reasons already discussed here.
HOWEVER, once you have written an original article it is not difficult to make a whole series of small tweaks and changes in word-choice, word order, sentence structure, as well as changing the title and then submitting THAT modified article to the article directories. Once you get used to doing it, you can modify an article several times over - also, as you work on a new version of the article, new ideas occur to you and so you can work them into the new version of your article.
The hard work is writing the FIRST version!
Another way to go about it would be to write the first version around a certain set of keywords and then choose a second set of related but different keywords for the second version and work them into it. That will automatically cause you to rewrite the article to accomodate the new keywords.
I don't think it is a case of "either original content on site OR article submission", but rather a case of "original content on site AND modified article submission"...
Finally, if you submit to the better article directories, real people really do look at your articles and click through to your site, so no matter what the spiders are doing, you still get people to your site by submitting original articles!