Google is much better than Bing and Yahoo because of the following reasons:
1) speed, results are returned very quickly - this was a big deal a decade ago, not so much today as most the other engines are reasonably quick now.
2) simplicity - the results are displayed in an easily consumable fashion.
3) search algorithm. google basically pioneered a way to rank pages to return more relevant (and more accurately stated, prevalent) results than other engines. They did this by ranking pages based off other pages linking to that page and calculating a score based off that. I.e. if you have a lot of popular sites linking to your page, then your page is considered more relevant for that keyword or term.