Maybe I need to fiddle around with the settings more, get some better filters in there. But part of the advantage of Google is not needing to fiddle - it knows that I probably want programming results if I search for "rust" and things like that. I'll stick Kagi out a bit longer, because I really like the idea of it, but I've been fairly disappointed so far.

EDIT: one specific criticism is that I speak English but live in Germany, so I typically want English-language results except around German-specific things where I want local results more. Setting my location to Germany results in a lot of German results for unrelated searches (e.g. documentation for some library, or information about an actor), but setting it to "international" makes it harder to find the local results I'm often looking for (e.g. libraries in my local area). Google isn't great at this either, but it gets it right a lot more often.