Which is the best article directory for you? That partly depends on what you are writing about. Buzzle.com, for example is one of the few article directories that really gets the readers for poetry and articles about poetry, but my business-related articles seem to be ignored when I submit them there. They do cover many categories, but they have developed an audience that is inclined towards certain types of articles.
Other article directories are not just oriented towards certain areas, but are actually meant for a specific niche. If you write articles on self improvement, for example, a great place to submit them is selfgrowth.com, although they will only take one submission per month at this time. Other directories take only articles about the internet, or only about outdoor topics. These niche directories may have fewer visitors, but they are visitors that are more likely to be readers of your articles.
The best general article directory, in my experience (I have submitted over 550 articles to 30 or more directories), is Ezinearticles.com. I could get all the traffic I need by submitting just to this one directory. There are good reasons to submit to more than one directory, however. Here are some of the things to look for in those other directories.
1. Direct traffic from the directory. Submit your articles to several directories. Them several weeks later, check your web site reports to see if the URLs for any of the directories are showing up as "referrers." Some directories are better than others at delivering direct traffic. Of course, if none of them show up in your reports, you may need to do a better job writing the resource box to get the reader to click through to your site (but that is a topic for another article).
2. The site is popular. Specifically, you want directory sites that have high Google PageRank. This is a proprietary measure of page importance that Google uses - you can find out what the ranking is if you install a Google toolbar. Regardless of whether they deliver direct traffic, I'll submit to a directory with a PageRank of 5 or 6. The incoming links created help boost the popularity of the web site.
3. Automatic home page placement. Some directories automatically put your article on the home page once it is approved. It appears under the "new articles" section or something similar, for a day or two. This means good exposure, at least until it is bumped off the list by newer articles.
4. The directory is easy to use. There is a simple reason why this is important: Time. There are too many easy (and good) article directories out there to waste time on those that want to complicate the process.
5. It is easy for webmasters. You don't just want your article to sit there. You want other site owners to take it and use it too. See if that is easy for them to do. If so, they are more likely to get articles at this directory.
6. Has clear rules. Article directories need to have clear "terms of use" or rules for both those who submit articles and those who take and use them. In particular, be sure that potential publishers are clearly informed that the articles must be unchanged and the links must be active.
The above guidelines are not all equally important. If a directory is strong in one or two areas - as well as the last - this is enough. Article directories that are good in all these areas are a blessing.