I love all science, though like any mother with several children, you just can't love all your children equally. Astronomy is my favourite. I have every book Carl Sagan ever wrote, and several biographies besides. I love everything about astronomy: galaxies, planets, stars, Big Bang, everything. But biology has always been a kind of poor cousin. I liked evolution and the history of life and how it kinda fades into things related to astronomy and geology. But the closer you got to know and taxonomies, and classifying animals, the less I cared. So, it shouldn't have surprised anyone that I have like 200 good books on astronomy even after culling through my library and getting rid of things, while I've never owned more than about 3-4 books on biology.
I decided to rectify that recently, and I bought all the books Richard Dawkins has written. I haven't the foggiest idea now when I will get around to reading them as I still have 15 books on the top of my entertainment center waiting for me to read from last fall, not to mention the 3-4 audiobooks I've been working my way through, like Atlas Shrugged. I also bought two books on climate change. One about the evidence, and one about the predictions. Should keep me busy for a while, and out of trouble.
Why am I so passionate about science? I've often asked myself this question, but it ultimately comes down to this: because I'm passionate about the truth. The truth matters. And science is the most reliable way we've ever found of finding it. And the reason I dislike most religions so much is because they run away from truth. Hard truths are the most important kind, and they run.