Roughly speaking, AddMeFast.com's usage is almost the same as ViralContentBuzz.com. However, AddMeFast covers more SNS sites and more SNS actions. For example, you can get points by share, like, follow an account on Facebook. At the same time, you also get points by sharing or like posts on Facebook. On ViralContentBuzz, only sharing is covered. Also, it seems there are many users on AddMeFast.com. As a result, my first day's experience shows that AMF is much better than VCB. The number of likes/shares/followers and whatsever are 100 times more than what I can get on VCB. Since both are free (freemium), I will use both in the future.
In short, AddMeFast.com is much more recommended than VCB.