Many people buy a camera based on the camera bodies specification, but when buying into interchangeable lens cameras, you are buying into a system.
I shoot Nikon for my SLR needs, sometimes Nikon have the best bodies and sometimes its Canon. Lets not forget Sony, Olympus, Pentax or Panasonic.
Look at the whole system, and think about the sort of photographs you take and what will help you get those photographs easier. You want a system that helps not hinders.
I currently have two camera systems, Nikon DSLR and Hasselblad. Both quite different and I could not say one is better then the other. Obviously the Hasselblad being medium format gives slightly higher quality results, but using it is slow and a tripod is essential. The Nikon has much to recommend it. The flash system is fantastic and the range of lens makes it far more versatile.
What might surprise people is that I have been after a third camera system for a number of years. This needs to be high quality, interchangeable lens, and small, something consisting of a body three lens and a view finder that can be packed into a motorcycle’s tank bag.
I have been researching and testing cameras at my local camera shop and after several years I am still no closer to buying one. Once purchased, while bodies may come and go the lens will be with me for many years.