I know it’s a matter of personal preference, but for me:

General search

1. DuckDuckGo - It’s really just Bing in disguise, but I daily drive it to keep some distance between me and Microsoft.
2. Bing - I know, weird choice, but DDG filters their results even after you turn off Safe Search.
3. Yandex - Great if you’re searching for stuff that Bing might filter, or the US gov’t might censor.

XXX stuff

1. Bing - Bing has been better than Google for years now, for images and video.
2. Yandex - Maybe better than Bing, but you need to translate a lot of results from Russian

Reverse image search

1. Yandex - Best, hands down. Google is actually 2nd best, just stay logged out and use private browsing mode.
2. Bing - Pretty good, but not quite as versatile as Yandex.