The best search engines on the internet will depend on the kind of information the user is looking for though there are some that are accepted by most users as being helpful such as; Google, Abilock's article, Metacrawler, AltaVista and Profusion.
There are many people search engines available. Which one is best depends on what you're looking for. Pipl.com allows you to search usernames and email addresses. Zaba Search allows you to find addresses. For more information look here: www.ask.com