DDG is just a wrapper around Bing and substantially worse than Google, smaller index and less up to date. Not needing a login doesn’t really guarantee you anything either, as they still can identify you by IP or device finger print if they want to. You basically have to trust their marketing that they don’t do that.
What makes Kagi interesting is that it’s actually right up there with Google in terms of results, while surpassing it in terms of features. Would I pay $10/month for Kagi? Nope. It’s good, but not magic. It’s still just regular Internet search and you’ll find most of what it finds with other search engines as well, especially when you hop between multiple. But if you want a better search engine and have the money, Kagi does feel like an upgrade, which the other alternatives just don’t.