Privacy oriented search engines don’t exist
Search engines queries are direct requests to the search engine which these engines need to look at. I would like to provide to you the definition of privacy “The state of being in retirement from the company or observation of others; seclusion.” It's impossible to provide a search query to the search engine and have it not reveal the senders query terms to itself and still function as a search engine. A “privacy oriented search engine” Is violating its own promise every time the server decodes and parses the search query sent. The word privacy, for search engines is a promise not an inescapable feature of the engine.
The harsh truth of the internet is, user count and brand recognition are all that matter. Value is created from direct control over services which are able to maintain a user base and appear to be respected authorities. No matter who you are, people enjoy feeling they are using the best product and users will often fabricate attributes about their product in their minds to fool themselves into such feeling. Privacy oriented search engines are one of such products, there are no ways of judging how “private” a search engine is, there are no indicators which we can look at to reveal the quality of the attribute. Its an invisible attribute which people have to believe on trust alone.