Google is just a no brainer. It's the biggest search engine and you'd find the most results there. Use Bing if you're curious and want to try something new, but Google will always be the "gold standard".
I have used Live Search in the past and did try Bing search when it was introduced in 2009, however, I have always loved Google search. There is no specific reasons behind my preference. However, sometimes I still use Bing to see how the certain keywords rank on Bing.