It may be Goliath vs. Goliath, but you don't need to pick sides - especially if you have in place a social media management tool like Sendible that can seamlessly post to them both. I believe that all social networks should be equal: each have their own collective gatherings of minds, opinions and user motives. Each also have their merits for different types of users who are often at different levels of involvement and engagement.
Facebook and Google+ make a valuable contribution to the way users can interact with businesses. One focuses on the inward premise of one's peer group and companies that are looking to build a brand by association with content that is shared on its network by your friends. The other is described as a "social layer" consisting of not just a single site, but rather an overarching "layer" which covers many of its online properties.
In a nutshell, Google+ is Google. It's providing millions of existing users established services from Search and Gmail, to Maps and Chrome, to Android and Ads and YouTube.
With Google + instead of the assumption that everyone is your friend, you put everyone in appropriate groups called 'circles.' People can be in more than one circle (just like in real life) and you can easily share something to some people or with everyone. With over 1 billion daily users of Google products, Google+ also enables you to reach the right people at the right time. Google searches deliver relevant results from your Google+ page, including recent posts, photos, and videos, right when they matter the most to your customers.
Say, for example, I noticed an advertisement on the train. When conducting an external search for more information about that company. I would most likely turn to Google (just as a vast majority would) for its regarded by many as the go to method for casting a broad net for information not just isolated to my friends. Just as the Hoover is often incorrectly substituted for other brands of vacuum cleaner, the term 'to Google it' is term already hardwired into the digital era. So in my opinion it is absolutely imperative that companies embrace Google +. The awareness and exposure you set there is likely to be the first contact an individual has with your business.