Normally I tend to avoid questions like these. The only widely-known photographer I'm familiar with both for his name and at least some of his work is Ansel Adams. However, I'm currently "reading" a book of his images, and the closer and further I look, the more I'm, not just amazed, but astounded. I expect that I'll find similar effects as I look into the works of other great photographers, but right now....
So far, and I think it's going to stand, my favorite Adams image is Trailer Camp Children, Richmond, California, 1944. The image entrances me, and the more I examine it, the more incredible it becomes.
I will say that this is not the only image that catches my attention... most of them have positively grabbed me once I stopped flipping through them and actually started looking at them. I really do admire his style. A lot of the effects he accomplishes in such a seemingly effortless manner are the same ones I've toiled through roll upon roll of film to achieve--and because I like the feel of that kind of image, not simply because I saw his images and want to copy him.