The Protaper files are the best I have used when it comes to rotary endodontics. My sales rep, Alexandra, is excellent. I have used their products for years, as I changed practices and still use them today with my own practice.
I had the worst experience with one of the employees at Dentsply, his name was Jarrad Jennings. He was dismissive to me, and blatantly rude as well. I will not be recommending this place to anyone based off of my experience with him.