bleach, in addition to not adding unnecessary chemicals, is also typically cheaper. 1 gal 6% bleach adds 6ppm to 10k, for <$2. Cal-hypo at my nearest pool store is $3+ a pound, which I think gives me 7ppm per 10k pool. so 50% more price, for 16% more chlorine- and the bleach is already dissolved, so no pre-mixing or powder residue...
As Aylad stated, the amount is based on your CYA, pool, etc...