I have heard good reviews about pex pipe, BUT I also heard good reviews about the poly pipe which in time turned out to be a disaster. I’m a great believer in copper water pipes. Too many new materials and equipment come and go making repair/replacement parts hard to come by. The choice is yours, as for me, I prefer to let others experiment and when it has been in use and trouble free for 5 to 10 years, I’ll use it. (I’m sure you’ll get different responses)