I have a Kagi account, and am pretty happy with the search results. But I don't like that I have to trust them not to keep a record of my search history, tied to my account. I have no reason to believe they are malicious, but I also have nothing -- aside from their word, which is worthless coming from someone I don't personally know -- to give me a reason to trust them.
If I'm doing something in private browsing mode, I fall back to DDG. Not only do I feel weird about being signed into something when I'm supposedly doing something "private", either I have to manually sign into Kagi each time I open a private browsing window, or install their extension, neither of which I really want to do.
So I'm torn; I'm not sure if I'll keep paying for the account, or cancel it and go back to DDG.
Then again, I also pay Fastmail for email, which gives them access to all my email. Arguably that's just as bad (if not worse) for my privacy than giving someone my search history. It's not clear to me why I'm ok with that, but uncomfortable when it comes to Kagi. I suppose email is inherently tied to me, whereas search results need not be? I dunno.
Regardless, this is the big issue with paying for something on the internet that you can also get for free. In some ways my search privacy can be "trustably" better with Google (via private browsing + Tor or at least a VPN) than it can ever be with Kagi, which is weird.