If you are trying to get visitors from the article to your site, and to sell to them...quality is very important....you essentially need to pre-sell. If you are using article marketing to build backlinks to increase the organic search traffic to your site....quantity is more important....I mass spin and submit to 1000's of directories...and gain about 200-300 links from each submit....many probably end up in the wrong cat, fail to submit, or fail to pass a manual review....but in the end I get lots of backlinks....and my sites do well in Google. Quality and quantity combined is a killer too if you have the time to spend ages crafting a perfectly spun huge article. If submitting for backlinks I try to get 30-40% original articles...the more original it is, the crappier the spin though, and the more likely it is to read like garbage.