Sorry, I'm far from an expert here. They started recently and just went out of closed beta I believe. I've been using it for a few months now.

They have a lot of nice features pulled from Google and DDG:

https://help.kagi.com/kagi/getting-started/index.html

I haven't done any objective tests, so can't really say much about search quality except that it definitely works at least as well as Google for my searches (usually tech or legal stuff), and it doesn't have ads. Whatever I'm looking for is usually the top result if my query is good and it's not something that's ambiguous.