Use all of them but definitly use google+ Get your google plus page going, make posts, get +1's from friends, family, business partners, etc and you will see your page rank in google go up. Of course they are going to watch google+ now and not FB as much anymore. Its their product.
I agree, use both of them. Google+ and Facebook each have their place in marketing. The great thing about Google+ is that most people rely on their traffic from the Google search engine and Google is starting to use Google+ in its search results and +1's are starting to play a factor as well. I feel that if you start using Google+ now you will be ahead of the curve.
Google plus is not just a social network. With Google plus login. You have the access to the whole Google services. But with facebook login, It just one service.
Google+ offers more professional services than Facebook alone. It's more convenient to use and I think its more for business purposes.
I think you should use both google+ and facebook, they both have different advantages as google+ limit its circle to 5000 members only
I use facebook, twitter and google + for social networking. I think many people had started using Google + and seo perspective having your website in Google + adds advantage to it
I am also not really find any reason to switch from facebook to google+. Though I have an account there as I use gmail, still not habituated to use that. It's not a easy job to going with many social networks as well. In facebook, we have already made our circle, and actually there is no reason to make that in another platform.