And Anhauser-bush sells the most beer and Toyota sells the most cars. That does not mean they make the best products in their respective spaces. What they are all doing well is marketing, like buying out Scott Kelby, or top NASCAR teams, and positioning products for mass consumption.
Ok, then…please define what constitutes the "best product".
Now…is your definition the same as mine? As my neighbor's? As the 347 people living in Manton, CA? As the 8,337,000 people living in New York City?
It's simply not possible to define a universal "best." But it's reasonable to assume that the majority of people buy the product that they think is the best, for them, meeting their needs in terms of features, quality, cost, availability, and innumerable other factors that go into such a decision. Unlike all the subjective opinions spewed across the internet and elsewhere, yours and mine included, it is an objective fact that more people have decided that Canon dSLRs and lenses are the best, for them…and have done so consistently for >10 years.