I wish they'd make it easier to adjust individual engine's weight, ideally right from the UI instead of a config file. Personally, after bumping up Google/Wiby and bumping down DDG/Presearch/Startpage (and disabling Bing altogether), results became much better. It still displays some results that only the latter engines turn up, but IMO there's noticeably less cruft.
Turning on Google/DDG etc results in hackingwithswift, avanderlee, developer.apple.com docs and SO at the top.