Although on a personal level, I don't agree with this, I still use myspace more than facebook, but to be honest don't really check either very frequently anymore. Facebook is now more popular amongst 17 - 24 year olds. Many veiw this as a good thing. One blogger airs their views about why they think Facebook is better off being the leading website amongst youths.
This person makes some good point which I have never actually thought about before, myspace's sex related ads and messy layouts, whereas Facebook is safer, and more uniformed. And in my own opinion, I have always thought facebook was a better method of networking, just because it's easier to do so. and also find more people you have things in common with!