Here is a couple of articles I found that deal with the subject of Ad-aware vs Spybot S&D. The interesting thing is that almost nobody out there clearly prefers one to the other.

http://www.aselabs.com/articles.php?id=125
http://www.flexbeta.net/main/articles.php?action=show&id=39

Has anyone ever compared these two products? If so, what’s your preference? Perhaps, someone can point me to some kind of comparison analysis of feature matrix on the Internet.