I used to use Altavista pretty exclusively, until at work one day some guy was using Google (this was about 5 or 6 years ago) to search for Microsoft Knowledge Database stuff because MS's own search engine was so junky that Google was easier to use to search with. Since then I'm not sure I've ever used a search engine other than Google. It's been kept clean and organized (something neither Altavista or Webcrawler could claim), is fast, and usually has what I'm looking for in the first 3 pages, if not the first 5 results.
Yahoo? It was nice way back in the day when it was a ranked index of sites on the web. Things just got too big too quickly though and their methods couldn't keep up.
daroga