"Mark, I'm with Rob, Mike, and Eric. It bears out what I've said on LuLa, probably ad nauseum: the image that makes you raise your camera usually is the best one. Cropping rarely if ever improves a well composed, well executed shot made from a first impression."
I must disagree. The statement would be true if (a) good compositions always existed in the real world in the same aspect ratio as your camera, and (b) you can get close enough to the subject to frame it properly. I admit it's particularly satisfying when no cropping is needed, but that's not often the case.