Red. Partly because it looks like it could be part of a Star Wars set. However, there's a little voice in the back of my head stating that the yellow one is technically a better picture. I can't put a finger on why that is, though.
As it turns out, those are my two favorites as well. I also like the yellow one I posted last night, though not as much. I think where I want to go with this is "flowers as alien landscapes." I really like the way the red center I posted a couple days ago looks like there are aliens rising up to eat you.
Yet again I find Myself drawn to this one as I can almost imagine that I can almost feel the softness of it's center. The fine details are so clear, but the yellow bloom is almost as captivating and would have likely won My favor had it not been competing with such a visual delight as the red bloom!