Id say google without a doubt. Googles search engine technology is years ahead of yahoo's and bing's. They index new sites faster, and also calculate every site's backlinks and other seo factors faster, so if you are actively doing good seo work, you move up in google much faster than in the other search engines.
They both good and popular, But i like Google, Because is fast and simple. Yahoo have too much navigation both left and right, And also advertise.
One says: IMO google, with Gmail, Adsense, Adwords, etc. It also gets far more traffic, and sites mostly get more traffic from google then frrom yahoo. other says: Yahoo is better in terms of services. They are also better at taking over services. The only real thing that google has that they do right is adsense and soon yahoo will have that nailed down as well. I do like google's search a lot better though. but me i love them both...
Google is always in top position than any other search engine. Yahoo is also good one for search engine program but it never beat google.
It's obvious.. Google is the best, No matter what Yahoo starts doing i guess Google will remain few steps ahead of it, It got an advance search engine unlike yahoo's...
I think google is better in all terms, because percentage of search ratio of google is 80 times more than yahoo. And most seo company prefer google rather than yahoo, so google is 100% bettter than yahoo.