I like duckduckgo’s interface and I feel they genuinely put a lot of effort to ensure people have a great experience using their search engine.
Whether its their !bang feature or integration with apple maps or their various themes. (Heck even their no js, search engine option is very cool too).
In terms of quality of links and interesting content, i havent come across a search engine better then marginalia[0] for that. But then i search for weird stuff, so who knows.