I don't disagree that the best selling truck may not be the best truck. I personally don't care. I will buy what I buy.
As to one BRAND out selling another, that is BS. The inference is which OEM sells the most. Sometimes that goes FORD's way and other times it goes to GM. Since the GMC and Chevy trucks are mechanically the same product with only cosmetic differences separating the two it is disingenuous to separate them. If that is what you need to do in order to help your marketing department then so be it, but certainly we are smarter than that here. At least I think so.