The one in color much better, the one in BW has lost all the detail in the flower, thats not something you want to do. I bet that a different BW conversion would bring a much better BW version, give it a try. Follow this link for an interesting color to BW conversion that might help you.
//av.adobe.com/russellbrown/ColortoBW.mov Please note that this conversion is not legal in Basic editing, but is great for images like the one you posted.
