Well if I were going to buy one I'd use NHN as he's sold many to forum members,
Although I saw one recently advertised on eBay which I thought was genuine, I asked about his and this were his reply;
"It comes with the software. It is not original but whoever told you they cause problems is talking rubbish as I've been using it for over a year on my Audi and never had problems, I have also done many coding and scans on peoples cars and they have been happy. At the end of the day, a cable is just a cable and is manufacturered exactly the same, only difference is you can either pay £250+ for one from Ross Tech or you can buy my'n that does exactly the same for just £50. I can show you it all working if you come and collect. "
I asked him that I heard non genuine ones don't work aswell -
Can anyone elaborate