Copper has worked great in most areas for the 40 years it has been used. There are a lot of areas in the IE with hot soil that just eats it up though. Up here a lot of people use water softeners. If not adjusted right, the copper will be pitted badly on the inside and eventually rupture (probably during a freeze). PEX is the future (present everywhere else), but it does take specialized tools. Parts are not easy to find at every hardware store yet. I have never used PEX. I have installed miles of copper, yet the winds are definitely blowing that direction.
BTW, PEX won't rupture in a freeze.