Spec and Giant
Personally I see a lot of Giants at the tracks/ events, they do seem good spec and performance for the money. Some many in fact that it's a bit same same to me. I think Specialized have a better reputation for longevity, I remember the 'giant's snap' saying of not so long ago. Specialized also have the 'cool original' reputation as being one of the first mountain bike companies. Still Giants keep getting the best reviews for performance and value so I don't think the numbers will be changing anytime soon.