There are times when competition is appropriate, and times when competition is not appropriate. Reading, in my opinion, falls into the latter category. That is particularly true when it comes down to raw consumption, though it may be appropriate to be more competitive when it comes down to comprehension and reading level. (I don't think that competition is appropriate, but it may work for some kids.)

On the issue of achievers: you don't have to be competitive in order to achieve, at least in the traditional sense of measuring one person against another. Quite often qualities such as diligence will produce better results.