Many sites list out advantages and disadvantages between both.
The average consumer will value copper more and when there is copper, you will see the listing agent highlight it due to the perception.
I have heard plumbers and GCs swear by both so I really look at it from a cost point of view. If it is minimal savings, I go with copper and if its major, I go with pex. We have done remodels with both and have not had issues with either in the last 2 years.