Ease of Submission
With so many article distribution sites out there, it amazes me that some still require their submitters to jump through so many hoops. When choosing one, you should look for the process to be as pain free as possible. Asking you to sign in is alright, but once they start requiring you to take surveys, confirm multiple times or give a blood sample its time to go elsewhere. These sites will never survive in the current atmosphere, so submitting your article may be a waste of time.

SEO Friendliness
This can be determined in many ways and is important because without SEO benefit, your article may never get past the submission stage. The first thing to look for is if they allow live links. These exist when you submit your web address and people are able to click directly on it. This single feature can have the most effect on your rankings so it is crucial. Another aspect to SEO friendliness is the way that the article submission sites urls are displayed. Static ones (ie. /category/example.htm) are always preferred to dynamic ones (ie. php?id=798). In most cases this means your article gets found and indexed faster.

Popularity
It does no good to submit to a site if nobody is ever going to see it. Right now there are three major article submission sites:

Article Depot ? www.articledepot.co.uk
GoArticles ? www.goarticles.com
Ezine Articles ? www.ezinearticles.com

These 3 account for probably around 75%-80% of the market. They get thousands of unique visitors starving for content to use on their sites and in their forums.

The best advice when choosing a submission site is to pick only a few and stick with them. These should be sites you are comfortable with and fit the characteristics above. Good luck and happy submitting!

Jason Rickard is the owner of http://www.yourfavouriteshop.com - Europes largest reseller of White Noise CDs