You answered your own question above, and also identified why app.net won't interest you. If you're okay with ads, then I think you'd get zero utility from app.net
If even Google is having trouble getting traction with a social networking product, I don't see why anyone is confident that a social network users have to pay for will end up with a large enough user base to be useful.
Maybe App.net will nicely take care of that. I would definitely like to see a social network that provides me with content I want for once. Google+ has come pretty close, but that'll rapidly change if it gains mainstream traction, although Circles could prove to be a solution.