I would also consider paying and for the reasons you mention. However, how much would you pay? i would want the service to be as good as the free alternatives. In order to drive genuine innovation and great features, the site/business would need the resources to attract the top talent. Therefore, would you be prepared to pay enough considering the competition is bankrolled by big advertisers?

For instance, at present Facebook makes just shy of $5 per user per year.

I think $1 per month could be reasonable, Spotify charges 5 - 10 times that. The idea is that you're changing the priority from building an amazing ad network to building an amazing social network.

The things that are good for users are nearly always bad for advertisers. Such as total privacy.