Well, off course Google is the top of the search engine because according to the survey report of 2008, more than 70% and the report of 2009 says that more than 80% of the whole internet traffic is coming from the Google so with this high ratio, we can't rely on any other search engine rather than Google....
I like google for its all advance features like Adsense,Adwords.iGoogle and so on.I like it also because of the accurate and efficient and nicely filtered result of advance search.Wide range of search criteria large amount of database are also important factors.
As for which one is actually "best", that's strictly subjective according to user of course. Ranking them is easy enough - Google first, Yahoo second and everyone else third. Bing is still relatively new but are gaining users and a reputation.
its google of course..because of their best algorithom,techniques and open source data..its really tough to beat google but yahoo have their potentiality also..