being able to block/downrank/uprank domains from search results, being able to block AI from search results, rewriting URLs (for example, reddit.com to old.reddit.com), kagi translate, bangs (ddg has them but qwant does not)
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.