Would you use an ad-free search engine that boosts ad-free sites?

For me - probably not. I don't mind search engines with ads, and in some cases the ads have contained what I was looking for.

Ultimately the quality of the search results is far more important to me than whether some of the results are marked as AD or not.

Not to mention that some of the sites I get the most useful answers from, contain ads (stackoverflow springs to mind).

Nah, I prefer the most relevant stuff regardless of the ads. I have a Pi-hole to deal with ads.

Definelty