I prefer "Orkut" (
http://www.orkut.com ) which is the "Google Facebook", as google tend to develop better software and ideas geared towards community developpment and knowledge sharing. Google has developpment project in communities not even related to computer or information technologies but about "green lifestyle" developpment.
In other words they are better in what they do, and they are "engaged" in the world society.
Also by having access to one of the Google products, you get a free online email account, as well as all the other free products or services on the web ( Blog, Mail, Calendar and much more...) All of those have the same username and the same password. Your username become your email adress on Gmail.
I'm just saying that because I chose orkut over facebook, myspace and all the other for the reasons already mentionned and I'd like to have some friends on it as well!