Actually it depend on choice of the person totally.Both are really different from each other, apart from one similarity that's both are Search engines. Google is the most popular search engine while bing provides quality results to its users. I think it's better if you will use both of them and understand the differences.
Since Yahoo sucks so bad these days, my search engine order of preference is: 1) Google 2) Bing 3) Yandex Sometimes I can find things in Yandex I couldn't find in the the two.