When we reference the best search engines, we have to reference from two different means. Considering that search engines serve a user intensive purpose as well as a business intensive purpose, the best search engines should account for each side.
Of course, this puts Google as the number one search engine. It is the most widely used engine around the world by users because (at the time of this writing) it offers the most choice, the most accurate results, and the largest database from which to pull. A user can translate a page into almost any language to make reading more comfortable, and it offers field limiting, like searching only government pages. It offers automatic spelling corrections and it does not need the inclusion of particles (and, in, etc) for recognition.
Yahoo! ranks second in the field for many similar reasons. With more than a mere 20 billion web based objects, Yahoo! has been able to retrieve information as fast or almost as fast as Google. It offers easy indexing and it allows for near immediate access to things like dictionaries, traffic links and keywords, encyclopedic, and even stock searches. The choice of field limiting is also quite competitive. Many users feel that Yahoo! is actually a better search engine than Google. However, for getting your web page noticed on the internet, Google outranks Yahoo!
With a total of more than 8 billion searchable web pages, Exalead has ranked third on the list of best search engines. No need to worry about the word AND, while it also offers a field search through its advanced search options. The simple automatic ranking gives web owners a chance to get recognized fast, and is also able to immediately translate a page into an alternative language.
Dogpile actually comes in fouth for its consistent use of helpful search suggestions. Most search engines are more prone to focus on corrected spelling while Dogpile goes on step beyond that and offers new and alternative search possibilities through active use of linking.
We have to include Bing.com on the list of best search engines for its innovation. As the user goes through the steps, Bing helps narrow down possibilities based on the previous search. Thus, you can go from trying to search out a restaurant to finding the perfect Italian place within 3 miles. It ranks well in web based business attention in part thanks to its newness.
What you want from a search engine is user friendliness, accuracy and the ability to refine your searches as you get closer to your answer. For being found online you want simple indexing and the ability to be recognized from links. Each of these best search engines qualify under these two basic fields.