You can argue all you want about the best this or most popular that, but there's really only one unbiased arbiter of greatness: the Internet. And here's what it has declared as the most important everything-you-care-about.
Let's do a little search on Google Images and see what subject people take a picture of the very first thing they unbox that brand-new digital camera. All you need to do is search DSC00001, and most of the results will be the first picture taken. (NSFW)