Best flat iron hair straightener reviews no. 3. Karmin G3 Salon Professional Ceramic Flat Iron. The Karmin G3 is a salon-quality flat iron and does a wonderful job straightening hair. It has tourmaline-infused ceramic plates like the FHI Platform Professional, rather than titanium plates like that of the the BaByliss. It is the highest priced flat iron on our list, at around $150.