But which to choose? At this point, both services have strengths and weaknesses for personal social networking. But for business? There's no contest: Google+ is better.
(Note that Google+ is still ramping up -- signups are closed due to overwhelming demand, but should be open again shortly.)
Google+ has not one but three killer features (and by "killer" I mean they might kill Facebook if Facebook does not copy them):
Killer Feature #1: Following, not Friending
On Google plus, you follow people. You don't friend them. That means you can choose to essentially subscribe to the posts of others without them subscribing to yours. Mutual agreement is optional. (If you search Google+ for "Mike Elgan" and follow me, I will follow you back.)
Google's following system erases two sources of Facebook fatigue. The first is that uncomfortable awkwardness that happens when you don't want to be friends with someone anymore. You have to "break up" with them.
Because people don't like to do this, they don't sever unwanted connections. So your Facebook Friends list has people you don't want to communicate with, and this limits what you post on Facebook.
The second source of Facebook fatigue is the sinking that nobody is reading what you post. Facebook uses a secret algorithm called EdgeRank that prevents your status updates from being delivered into most of your friends' New Feeds. Google+ actually delivers your updates to everyone you designated.
Even more "killer" is that people don't even need to be Google+ members to get your updates. If they're not members, they get your post via e-mail!
Some people like the friending idea, and some people don't. But for business, there's no question that following is better. You're free to follow dozens, hundreds or thousands of colleagues, partners, industry leaders, suppliers -- anyone you want -- without confronting them with a forced "will you be my friend?" situation.
Killer Feature #2: Social Circles
You don't need friending on Google+ because the site forces you to put each person you post to in mini networks, called Social Circles. You can have a "Family" Social Circle and a "Friends" social circle, which is nice, especially for teenagers.
But for business, Social Circles are ideal. You can have "Staff" or "Team" social circles, "Customer" or "Client" social circles or any professional collections that make sense to you and your business.
In the past, professionals have resorted to e-mail newsletters and mailing lists; and company e-mail and chat networks. No more. Google+ replaces all that effortlessly.
Better still, Google+'s Social Circles ends the single worst feature of Facebook: social overlap, where people in different spheres of your life see the same posts.
On Facebook, you want to post pictures of Vegas, but you called in sick to go there. If you post, your boss knows you lied. If you don't post, then you're being prevented by a Facebook flaw from doing what you want online.
Social Circles lets you go ahead and post those Vegas pictures to your friends, without making them available to your boss (or your mom).
Social Circles encourages business connections because you can't really have people from your professional life have access to your personal life. Because some college buddy might tag you in some old frat-party picture on Facebook, there's no way you're going to "friend" clients. But on Google+, mutual following is socially safe.
People can monitor their professional feeds by day, and personal ones by night. Social Circles are better for business.
Killer Feature #3: Hangouts
Facebook today announced Skype integration for one-on-one video conversations initiated on Facebook. There may be some people out there who aren't already Skype users who will be pleasantly surprised by this feature. But not many business people.