I can't comment on that without some bias. If you personally believe Google's DNS is a potential threat to your privacy, my best advice is to use whichever DNS service you find to be most trustworthy, be it Quad9, your ISP, Cloudflare, etc.
However, I'm really not sure the whole recent debacle over "don't be evil" is really relevant to perceived ethical issues regarding Google. It's not like the motto became "actually, yes, be evil" - as far as I know, it became "do the right thing." And honestly, company cultures are all much more than just a motto.
I speak only for myself, but my feeling is that trust is very personal and if you don't trust Google, that's your right. All I'm discussing are things that I know, not trying to tell you who or what to trust.
I can’t say I trust Google overall (and have been gradually replacing my use of their services with competitors), but I do think that they abide by their terms and conditions generally, so thanks for posting a link to the 8.8.8.8 docs; they seem pretty clear-cut.
While Google's business model certainly relies on collecting and monetizing user data, I have yet to see any cases of abuse on their part. Rules for employee data access are very strict and I don't know of any cases whee they directly share data with third parties (excluding government demands).
For me, this makes them one of the most trustworthy companies when it comes to handling my data. If you know of any cases otherwise, I would love to hear about them.
Don't be evil was NEVER abandoned. That was reported by right wing media and picked up by mainstream media without checking. Here is the the latest employee conduct statement.
"And remember… don’t be evil, and if you see something that you think isn’t right – speak up!"
It is a business that relies on collecting data, monetizing it, and using it to further reinforce its position.