Article Comparing Loislaw, VersusLaw & National Law Library
It offers a pretty good comparison of search features and ease of use. However, the author fails to include pricing information for Loislaw since Loislaw doesn't include this information on their Web site. But he does say that it's "probably very expensive" A simple phone call to Loislaw would have provided the information. As of June 2004, packages range from $90/month unlimited for one state to $250/month for all state and federal unlimited.
Also, very little mention is made of the content of the databases. In my opinion, this is a major factor to consider when choosing a online legal research system.
All in all, a useful, if incomplete, analysis.