I chose Bing four out of five times, however I was able to correctly guess which searches were provided by which website, and the searches I used were very generic (names of shows, etc). Naturally, a search displaying videos would have an advantage.
Regardless, I use DuckDuckGo. DDG is fantastic for mathematical/factual searches, for quick information (via instant answer box at the top of the search), and its privacy policy is a refreshing change to most search engines. It has a very minimal interface, much like Google started off with. It allows me to directly search Bing, Google (images, news, regular search, etc), Amazon, YouTube, Wikipedia, Wolfram Alpha... actually, just take a look at this page for all of the sites I can search directly from the address bar. !bangs are probably my favourite part about using DDG, actually. I use them all the time.