Which articles will make you the most money? All depends on where you write for. If you write for Facebook, a very short intro is much better than an entire article on your wall.
On the other hand if you write for blog then a long article is much better.
The ideal article length depends just on the situation and the topic. There are topics that require few words to be well explained, where as complex topics requires a lot more text to explain to the user very carefully how it works or how it should be done to work.
If you write for your own blog try to see which articles rank higher or which articles attract the widest audience. Most people love to read short articles because the number of people that read the entire article lowers with the higher number of words.
Book like websites are the best websites to write but since you need to write so much and the return is so little because most people simply do not want to read so much, maybe you should make partitions of the knowledge. For example, for micro blogs write the title and the intro, for general blogs write the article but the full info write just in Wikipedia like sites. Very long articles with more than 10000 words are book like articles and should be places onl in book like websites.