I’ve used the CHI’s. Theyre amazing. Thats all that my stylist will use. Mine has lasted about a year and I’ve got really thick curly hair. Haven’t tried GHD’s (I don’t think), sorry

I think straightening your hair a lot is bad for it. But having said that GHD claim to have a technology that is less damaging. I have one and use it daily, my hair is fine. As in OK. It comes with a manual and explains how to use it for different effect, plus sometimes a CD. Make sure you use good heat spray of cream protectors from heat while using them. I am very happy with mine. (Make sure you get the correct GHD size for your hair length.)