I definitely prefer the crown logo, I've always seen the rose logo's as kumi, too, but more when she was in her secret mroe girly era. The crown logo is more 'mature', I think. I think she changes her logo depending on how she and her music changes, which is cool.
Although it does mean there is no never a logo really recognized as kuu's trademark, like Ayu's A. Although I do recognize the crown as kuu's trademark since Kingdom.
I really don't like the spikey KK logo though. D: The ones that form into a heart are kinda cool though!
Does anybody have more good HQ images of Kuu's make-up?