Nikon and Canon are the most popular cameras among professional photographers within their class. Neither could be called a "best value". Professionals use the system that best meets their individual needs. When you buy a single-lens reflex camera (SLR), you are not buying a camera - you are buying a camera system. This is true whether you purchase a conventional film SLR (35mm or 120) or a digital SLR (DSLR). Professional photographers buy into a specific camera system to suit their own needs, which may not be the same as those of amateur photographers. A camera system consists of a range of camera bodies, lenses, and accessories (e.g., flashes), that have been designed for the needs of photographers ranging from casual amateurs to professionals in very specific fields. The most important component is probably the lens. Both Canon and Nikon make superb lenses, but for a price that few amateur photographers are willing to spend. Can an amateur justify spending the better part of ten thousand dollars for a 400mm or 500mm lens, when they can buy one for well under a thousand? Both companies make equally good entry-level lenses that are much less expensive and of lesser image quality. For example, the Nikon 17-35mm f/2.8 zoom is about three times the price of their 18-35mm f/3.5-4.5 zoom. Is the ability to hold the aperture at f/2.8 over the entire zoom range important? Is the higher sharpness and lower distortion of the more expensive lens equally important? If you can’t answer yes to these questions, don’t buy the more expensive lens. Amateur, advanced amateur, and professional camera bodies are designed for different purposes. If most of your time is spent taking holiday snaps and the family at Christmas, any entry-level DSLR would likely suit your needs. Don’t spend money on features you don’t plan to use. However, your needs may change if you take up photography as a hobby. Canon, for example, has become the most common SLR for sports photojournalism. Canon SLRs have been considered to have faster and more accurate auto-focus systems than Nikon SLRs and a better selection of lenses with long focal lengths. On the other hand, Nikon SLRs are considered to have a more accurate metering system. Which is most important to the professional? If that pro work in sports photojournalism, it is very important. However, that professional will have very different needs than one who specializes in portrait work. As far as features and robustness are concerned, there are much greater differences between high-end and low-cost cameras made by the same manufacturer, than between the products from two different manufacturers at the same price point. There are substantial differences, for example, between the Nikon D2XS (professional), D80 (advanced amateur), and D40 (entry-level) DSLR cameras. Expensive SLR and DSLR cameras are more robust and reliable than entry-level models. You get what you pay for. Professionals use their cameras more frequently and in far harsher environments than most amateur users and need robust and reliable cameras to earn their living. In the end, selecting a specific camera system determines which features you will find available on the camera bodies, which lenses can be used with those bodies, and which accessories you can use. It will also determine compatibility with older equipment that you might want to purchase or already have on hand. For example, only a few Canon FD lenses can be used on the current EOS mount bodies and those only with a special adapter. On the other hand, a non-AI Nikon lens (pre-1977) can be used on most new bodies, albeit with some loss of features.

Too close to call. They both are in the right business. Both make fine cameras. In a tie breaker I would go with Nikon.

They are both fine fine cameras. In the digital age they are near equal. But I would lean towards Canon. Between the cameras themselves and the value, I think you'd never be disappointed.

Yeah, as you can see it just depends on the person and what they need/ like. I personally love both of them and I own a nikon digital and a canon SLR and would not trade either. I do know canon makes all of their parts though.