Well , you've certainly started a debate that will endure forever , but personally , having worked with both products , PEX is a better product . Now granted , the 1st time i used it
I was not impressed , cause it leaked.......NOT because the product was at fault, it was because I did not understand how to use the product !
The trick to using Pex , is to make certain that the fittings seat, they MUST be pushed together with force, and if you do not push with force to get the seat to seal, it leaks .
Therefore , when using PEX , you have constantly to be aware of leaving room to make your connections -Properly !
The beauty of PEX is that it bends , it is flexible and decreases the labor factor ,although the connection costs are often 100-300 % higher than copper , but again , it can cut labor costs in half and it is safer to work with, NO FLAMEs!