If you are worried about your privacy, Google is way scarier. If you don't use Facebook as a social networking site, the data it will have to you is minimal. Can be made even smaller with a couple of extensions available on all browsers.
Now Google owns one of the largest ads network in existence, which means you're being tracked by Google every time you set foot on any site that runs ads. Plus, those that don't probably use Google Analytics, which is also tracking you. Plus, there's Youtube, Google office suite, GMail (even if you don't use it, half of your correspondents do, including many companies so you don't even know by domain name that you send data to Google). Plus, Google Drive, etc. Plus Android, plus Google Play, plus Google Maps, etc. The amount of your private data that is going to Google, if you have any online presence, is stunning. Google is clearly scarier.
Now, if you're worried about these data being used in partisan political battles, the picture is different. As we know by now, both US political tribes has been able to successfully collect and use Facebook social graph data for their purposes. Facebook management remains more or less neutral so far on this question - while the top management undoubtedly belongs to the blue tribe, and, as we've seen, has been glad to provide access to blue tribe campaigns, the red tribe has been able to use the data too. For Google, again, the company is managed by the blue tribe, and openly sides with it at every opportunity, but we don't know anything about how or whether the data is used for political purposes. If you are concerned about the red tribe gaining the same access to private data and control over mega-corporations as the blue one has been enjoying so far, Facebook would be scarier for you, while Google would look pretty safe - even though they have a lot of data, people with correct tribal affiliations are guarding it, so no need to worry there.