I think that dating site are better than social networking websites, because they are specialized in dating services. However, bottom line is, that you are gonna go on a blind date, so to speak, and from this point of view it does not make any difference that you met the boy/girl on a dating or social networking website
You can meet different type of people on social networking sites but dating sites are more focused specially if you are seeking dating in specific dating niche, such as dating for seniors, single parents, occasional dating, travel dating etc, in such case dating sites are more useful and its more likely that you will meet like minded person.
Most people go online cause they can't get one in real life. but the problem is. There would be questions like, what are you doing tonight or their relationship status are hidden. Try facebook.com or Jiopo.com because atleast you know if their available or not.