flute like whistle

I was just curious…many people talk about whistles that sound like a flute.
Is this preferable or not, or is it matter of preference.
WHAT exactly makes them flute like (what to look for in a whistle then) and WHICH whistles do sound flute like (examples?)

Berti

I think the bore (conical or cylinder), the shape of the windway, the blade and sometimes “walls raised around the windway” has got to do with what makes a whistle sound like a flute. Some say Susato sound flute-like, and many would agree that Copelands do much more. There are, however, some who would tell you that even the flute-like-ness of Copelands is “cheap” compared to real flutes.