I have both, and I must say, I like facebook a whole lot better. I have not been on myspace for at least a year. For some reason I always wanted one, and my mom was super-crazy like, "NO. SOME CREEPY OLD MAN IS GOING TO FIND YOU AND RAPE YOU AND KILL YOU." Thanks mom. Even though I knew there was the risk of having a creepy man stalk me, I was pretty sure I'd know what to do when the situation presented itself. Hmmm... pretend I get a message from some random smelly old guy that says, "We should meet some time, where do you live?" What does she think I'm going to do; say "LOLZ, LYK, SURE HERE'S MY ADDRESS :-*!!"?? Yeah, I don't think so. I'm not that dumb and definitely not that irresponsible.
Anyway, I like using facebook because it is very easy to use and I don't know a whole lot about internet-coding-excitementness. I don't think any of my actual friends use myspace. However, I'd say that about 90% of my real friends have a facebook.
There are plenty of stalker sites, but I don't think facebook is really one of them.