The vanity search test breaks down for those of us blessed with highly generic names, so I gave it a run on my editor, Josh Levin (putting his name in quote marks for exact matches). Josh fares the best on Cuil, which, unlike all the other search engines, is not squeamish about listing lots of results from the same source; 10 of the 11 front-page results are from Slate. Both Google and Ask give top billing to Slate articles, while Yahoo and Live Search give the No. 1 spot to sites devoted to people of the same name—josh-levin.us and joshlevin.com, respectively.
The differences here demonstrate that a search engine has to choose between foregrounding a close match or going with a site with lots of authority. By putting a Slate article as its top result, Google and Ask reveal a bias for authority over closeness. By linking to sites with the keywords in the URLs, Yahoo and Live show a preference for closeness over authority.
Search engines ultimately aspire to produce results that are both intuitive and correct. In the end, your decision about what search engine is right for you may come down to a matter of opinion: Who spews more disinformation, Wikipedia or the White House?