DuckDuckGo — A good search engine, default in the Tor Browser. Positions itself as anonymous. Information searches in clearnet. Well-publicized resource, a large audience of users.

Torch — Not the worst search engine, over a million pages indexed. It only searches the Tor network. М

You can buy ads for bitcoins and place your banner! A lot of scam is advertised. Be careful.

Ahmia — A project of an American non-profit organization that develops anonymous communication services. There are ads, but not much. It is also available on clearnet.