I pay for Kagi because it does not have any form of advertising or “sponsored results”, and it consistently gives me the best results of any other browser I’ve tried.
Apple supporting this would not be hard, as with all the other search engines the search is just a query parameter appended to the url, they could just provide a template string for “unsupported” search engines.
Safari is great. Quick Look, syncing tab groups, good touchpad navigation, non janky UI and probably more are my reasons for using it. I just wish it was possible to have shared bookmarks with Firefox which I use on Linux (or have an actual Linux port of it even but that's even less going to happen)
Safari power usage on mac is incredibly low compared to Firefox and other browsers. If you're on battery while on Mac hardware I highly recommend using Safari