We ought to add another party: the public. Perhaps data should be able to be used for the public good, and we should be able to participate in deciding what data is collected and how data is used.
In this case, having data about what ads are seen, by whom, and why they see those ads, seems like it could lead to us better understanding how FB and other companies algorithms are segmenting the population and how certain ideas proliferate within those segments. This seems beneficial to the public, since as we've seen over the last 5 years or so, these platforms and the way they choose what information we see can have drastic effects on the economy, politics, etc. If I had a choice, I would choose to continue collecting data about the behavior of advertisers and the platforms that serve them for that kind of analysis. But we don't have a choice, because facebook "owns" that data.
A number of people in this thread have referenced Cambridge Analytica. When Facebook does choose to share data with other parties, we have no say over what data is shared with them or what they may do with it. We don't even get a choice in how Facebook internally uses our data. Instead of democratizing the decision of what data is collected and how it is used, the FTC applied the rules of private property and fined FB for lack of privacy.
The public got nothing out of that situation. Facebook now is more defensive of their ownership over our data, which also precludes us using it for the public good.