What private search engine do you use? Why? (privacytools.io)

I use:

https://infinitysearch.co

It's Private and it's open-source! also, it's a search engine (not meta-search-engine, even if they retrieve results from others they have their own crawler and index)

I'm not sure if it's necessarily private, but YaCy has been awesome. It's a decentralized search engine that has surprisingly good results in my experience.

https://yacy.net/