As far as types I believe its broken down as 191 or 192 and is a refference to the number of amino acids . 191 is generally what I believe to be considered real GH.
As far as brands theres a lot, like Riptropin, Hygetropin Kigtropin , or the brands that youd find in Pharmacies in the US like Serostim, Lilly , and Tevtropin. Difference being Pharma grade vs Chinese aftermarket. I have run Lilly and Tevtropin, but everyone swears by Serostims. Best price Ive seen is a grand and up for a box of Seros though, so for me Hygetropins and Riptropins are how Ive gone.
I always blood test my HGH by measuring both Growth syrum ind IGF in blood levels, and although I have had bunk HGH a couple of times most has been good. But even though the blood test shows as good supposedlky the results from Pharma are far better with less side effects. I find if I run more than 4 ius a day my hands go numb like they've fallen asleep.
Oh and one more thing to consider if you are planning on plopping down several K for Pharma, is that the Chinese and other countries have gotten very good at counterfeiting boxes and labels, even scratch off verification codes and batch numbers so unless you really know your source you may still end up with Riptropin or the peptide IGF in a bottle labeles as Lilly or any other well known brand.