Nutropin and humatrope are both top of the line products, as is Saizen, Serostim and others. In fact, all rhGH is essentially the same in amino profile, otherwise it would not be "human", and would not have FDA approval.
You absolutely can not go wrong with anything from Genentech (nutropin). They were the first company to receive FDA approval to sell for medical use, a recombitant synthetic human growth hormone, and continue to pioneer the industry.
It really just comes down to price and convenience of use. I have used both and been very happy with both.