Refdesk is not a search engine, it’s a reference website. It is, in effect, a virtual version of the sort of thing you might find in the Reference section of your local library.
A good starting point for anyone wishing to find information, a picture, a recording or a video that they can reuse without falling foul of copyright law is the Creative Commons search site. As well as a good starting point, it’s a good one-stop shop, given that it covers such a range of media types.
Ask goes back a long time. Originally called Ask Jeeves (and still called Ask Jeeves in the UK), it features a picture of an English Butler. Butlers have a reputation for serious quiet and efficient service; does Ask make the grade?
Is Bing a sort of poor man’s Google? There is always a temptation to compare any search engine with Google, but each has its own strengths and shortcomings.