I prefer the colour, you're losing detail in the black and white, they look over-messed with (yeh, thats the technical term! )
I think that flowers in general always seem to lose something in black and white - I can't remember who it was but someone posted a rose a while back in colour and black and white and the black and white rose looked a little lifeless. Its the same with these.
The colour ones seem a tad over-saturated (purple is a really tough colour to get just right), but I like them better than the black and white, which to me just seem lacking in detail and a bit boring.