i can also argue that both canon and nikon provides a superior IS/VR system. the benefit of having the IS system on lens rather than body is that the IS doesn't age with the body model.

For example, canon recently introduced the 4-stop IS system on the newer lenses series such as the 70-200 f/4L IS. when using an older body like the 10d or 20d, it will probably provide better image stabilization than any pentax model that came out around the same time.

the external image stablization system generally provides better flexibility.

the part where canon and nikon comes on top are their lenses selection. Canon offers a wide variety of extremely strong and sharp telephoto lenses whereas nikon offers a wide variety of sharp wide angle lenses.

^sadly nikon lacks primes. Although the 14-24 and 24-70 are sharp, the 14-24 outresolves any WA prime nikon makes. It's such a good lens that people make adapters to mount it on their canons.

The 14-24 is as sharp as any wide angle prime out there period. The 24-70 is sharper than the canon 24-70, and is almost as sharp as the Sony Zeiss 24-70. The Nikon 24-70 @ 50mm is sharper than the 50mm f1.4 G at all apertures, as tested on a D3x.