In think twitter is the best social networking site as it has many followers and I can add as many followers as I want in my account. Also it is really helpful to divert the much better traffic to my site. Also it has best promotional techniques for the promotion of the web site.
It depends on where you are. In South Africa, Facebook is by far the best. People are just getting into Twitter, where as other countries Twitter is huge. Everybody here has a FB profile, that is why its the best is SA, and most other places.
I was using Orkut initially but i got bored as it became monotonous with the scraps. SO now i prefer Facebook as it has lot more ways to entertain rather than just scraps
The best social network sites are Facebook, Twitter, My Space, You tube, Hi5, Sqoot.They are best site, where we get quality traffic and back links towards the website.
If you want to do it in U.S, facebook and myspace would be appropriate. Orkut for South America countries such as Brazil, it works for Mexico too. I used to be on hi5 as well, it is mainly for European countries.
I would like to say that Facebook is the best... It has many features, it has good apps. And the most important is i can connect with my friends, because they use it