I've been using Kagi the last few months. I've never had a reason to complain about its search results - they seem to work plenty well enough day to day that I don't really 'notice' them. Like most, I now search reflexively, as an extension of the mind, so I only 'notice' search when it's bad.
What really excites me is that is that I'm paying them. That sounds odd, but seriously. It's incredibly refreshing to know that the company providing my search results has an incentive to make things better for _me_ and not a legion of advertisers. With Google I can't help thinking about every keypress being logged to optimize sales pitches at me. I just don't feel that with Kagi, because I'm paying them.
Sure, they might be logging every keypress (I don't actually think they are, but you never can tell) but even if they were, I could be reasonably certain they were doing it to retain my subscription, which probably means making my search better, not selling me other stuff.
It's a priveleged position to be in, and the economic argument isn't watertight, but in the "search as a brain extension" space it still _feels_ premium, because it creates trust. And that frees up brain space for other things - like where the hell was that article I was looking for?