i don't understand why people compare tha two, as i think both are strong in their own areas like yahoo is good for mailing and its sports and othre news, Google is very strong with its web searching
I am dead sure that both search engines are good & result oriented but as here we are compare both so I am not hesitate to elaborate that Google is best because it is largest..
Google and Yahoo both are very good search engines and i do use both of them but i don't use yahoo serach engine too often. but i do use other yahool services often such as Yahoo mail, and yahoo messenger.
If i had to choose between the two i would go for Google as Google send more traffic for my site and also it indexes my site faster and better compred to the Yahoo.
From the search point of view, both the search engines Google and Yahoo are important. Since Google has a 65% search market, Google fares better than Yahoo.