Personally, I couldn't care at all who sells the most of what and to whom. When we shifted from a DSLR-like point and shoot (Nikon CoolPix 5700) to a true DSLR (Canon 20D), we went Canon over Nikon for three primary reasons: better sensors; better (and wider range of) lenses; and better marketing attitude.
Better sensors: Canon has CMOS, Nikon had CCD. I'm the analytical type. I look at facts. No amount of Nikon press could convince me that CCD sensors were better than CMOS sensors.
Better lenses: as true n ow as it was then. This is not to say that Nikon doesn't have some fantastic lenses; they do. Canon just has more of them, and over a much wider range.
Better marketing attitude; Nikon's marketing attitude sucked, and still does.
First, there's the CCD versus CMOS thing, with Nikon blatently pushing CCD as the better choice, even though CCD sensors are demonstrably noisier than CMOS sensors (and always have been). But, of course, CCDs are demonstrably cheaper to produce. Nikon should have simply kept their mouth shut instead of badmouthing the competition.
By going with CMOS for their top-end bodies, Nikon is tacitly admitting that they were wrong and Canon was right.
Then there's the APS-C versus FF thing. Nikon blatently espoused the concept that there was no benefit to full-frame over APS-C. You could spread that marketing on your veggies to make them grow! Only a person of the type beloved by P. T. Barnum would believe that hoopla, but then, old P. T. was correct. And Nikon sold lots of APS-C cameras, to professionals as well as to consumers.
Nikon now offers full-frame in their top-end bodies. Again, Canon was right and they were wrong.
Mind you, Nikon has quite a few good and even some great innovations. But I have never regretted our decision to go with Canon for an instant.
