Also the fact that their contract requires them to whitelist Microsoft trackers is something to be wary of.
https://brave.com/privacy-features/
https://github.com/brave/brave-browser/wiki/Deviations-from-...
Brave for Mac is not Webkit-based. It is Blink and V8.
Practically, there are only two rendering engines left, 1) WebKit (itself derived from KHTML) and its derivatives such as Blink, and 2) Gecko and its derivatives such as Goanna, (though I guess somewhere someone must be using Flow, which apparently is not based on either, but it is proprietary, thus it will have no derivatives or be used by any other browser other than Flow).
(I know Brave is Chromium based)
[0]: https://developer.apple.com/documentation/webkit/wkwebview
That said, it has a cleaner interface than Brave, and it has that fire button from DDG Mobile that deletes everything except for cookies on sites you "fireproof". It's a really nice compromise between "save everything until you delete everything" and "incognito mode" that I wish other browsers would adopt. Plus it uses WebKit so theoretically it should be fast and battery efficient like Safari.
In my opinion there isn't much reason to use DDG Browser unless you really like the fire button. If you want a WebKit browser, Safari with the AdGuard extension blocks ads and trackers, has extensions including more password manager options, and has its own email relay feature. Otherwise Firefox and Brave are excellent and cross-platform.
Doesn't really have other features or support for extensions from what I've seen.