Somewhat frequently, friends, neighbors and even tumblr followers ask my advice on choosing a camera, or even just a camera brand. My reply generally parrots what my first employer told me when he handed me a Nikon FE-2, as we were about to go out on my first editorial assignment and I objected that I was used to a Canon body: the camera is a tool to accomplish the job. It’s a hammer; pick the one that does the job best.
It used to be said that, “lenses are an investment; bodies are disposable,” and while modern DSLRs certainly seem to age more swiftly than their film counterparts, that adage is still fundamentally true.
If you have never used an SLR, rather than spend all your time deciding between which $1,000-3,000 body you desire, you should think about what sort of photography you plan to pursue and then research what lenses best suit that style. Then, look at which manufacturer offers high quality lenses in that range and once you know which lens(es) will be your first purchase, then decide which body.
A low-end body can make amazing photos with a high quality lens, but a high-end body will be hampered by slow, inexpensive kit lenses and the like.
These days, Canon and Nikon are essentially neck-and-neck, in terms of their bodies, but Canon’s EOS line holds an advantage over Nikon in that 99% of the EOS (EF-mount) lenses made since 1984 will work on any EOS DSLR. Plus, inexpensive adapters are available to mount Nikon, Olympus, Leica and all manner of other lenses onto an EOS body. (I even have a Soviet-made 50mm pancake that I’ve adapted to work with my EOS bodies.) Nikon, on the other hand, has made recent bodies that are physically incompatible with lenses made just a few years ago.
Pentax, Olympus and Sony make very nice DSLR bodies, but their lens offerings are much more limited than what’s available for Nikon and Canon.
Day-to-day, a Canon EOS is my walk-around camera, but I also use cameras manufactured by Holga, Zeiss, Nikon, Mamiya, Polaroid, Pentax and Fuji — whichever tool is the best one to accomplish the job.