I don't know how those search engines evolved, but last time I checked (a few years ago), Qwant was the worst search engine ever, and DDG was pretty average. I don't know how Kagi works, but it's good for every query. I usually don't recommend it because it's expensive ($10 a month) but it really changed how I work, especially for programming topics.

As an example, Qwant still uses w3schools as the reference for C++, which is some "4chan trolling" level of stupidity.