Cork won't work very well
Good to see you've your priorities right for uke design. Personally I'd rather consider getting the uke sounding like I want rather than looking a certain way. Any and all of the tried and true uke top woods (and there are plenty- plenty more than any other stringed instruments) can be used to make very nice, if different, sounding instuments.
PS I really wanted to give a stupid answer but couldn't think of anything funny enough (top marks to Ken).