The best one is one that you get custom coded ... Problem with those open source scripts is that they can be hacked easily and you have limited ability.

Just tossing up a article directory today is not going to be the best thing to do. If you article directory is not going to offer something of great value and offer what other article directories do not offer then you are going to have a hard time getting it going.

If you are planning on putting up an article directory just to use as an adsense farm then you need to rethink your plan seriously. Many of these types of article directories will be going out of business soon enough because they offer nothing to the authors. Some have already went out of business and more are going to follow.

If you are interested in putting up an article directory then get one custom built, offer what others do not, and use a paid model and not a free article directory..

Just my opinion ...