I like Facebook. main reasons are it has lot of things unlike other social networks which would keep you active. Also good place for webmasters to try to grab some traffic. Also their social groups can be very useful.
Myspace has turned into the place where the youngan's hang out. Facebook is for the older audiance. Since I am older, I tend to like facebook. However, I think all of the application invites are really going to ruin facebook.