best thing to do is not use any at all.
as for myspace, it has a lot of spammers and advertisers, which can get really annoying. i personally don't think myspace is THAT organized but a lot of people use it regardless. i don't know about the copyright thing. it has less features than facebook i think, like the events stuff where you can invite people, or show people that you are RSVP'ing to an event, etc. but both are pretty much the same, and you will always get to choose what info to show or not to show (for both facebook and myspace), but just keep in mind that you shouldn't put too much REAL information up there in the first place :/. there are a lot of cases where people steal others' identities and they don't even know it.
i use facebook more. :D
i have used both for a long period of time. about 4 years for myspace, almost 3 years for facebook.