First post here! I think that in general, you can estimate the revenue you would be getting for each business model. There are several options here.

1. Donation. As far as I know, most users will not donate. Unless you make a donation banner as intrusive as Wikipedia, 99.9% of the user will never donate a single penny. I am new here, but if end up using Hubski on daily basis. I would not mind an annual donation of something like $5 (which is what wikipedia asks for). You can try to put up a donation banner like that periodically. Wikipedia publishes their numbers, so it's possible to get an estimate.

2. Ads. Most users will hate it. You can start by making them unintrusive with good intentions. For example, 1000 views per day for YouTube videos makes (very) roughly $100 a month. I don't think the numbers will be that high for Hubski since ads have to compete with contents that are always more interesting. Most users won't click on ads. Until you have a hell lot of users to cover your salary, this model will just kill users experience.

3. Subscription based. This is can potentially to provide a continuous stream of income without slowing down the growth or killing users experience with ads. If you give all users basic features and give paying users extra features and bragging rights (thus making the price worthwhile), this could work really well. It will be similar to Reddit Gold. The revenue really depends on what features/bragging right you give to paying users.

I think the best solution is to avoid ads as much as possible. As you said yourself, ads could potentially turn hubski into something that "is beholden to those parties that buy the information and views". When your priority shifts away from the users, you end up with the shitstorm that is happening on Reddit right now.