Don't really like PVC...PVC is light (compared to it's usage), durable, and resistant. Most heavy duty mold/mildew resistant shower curtains are made of PVC. PVC produces harmful fumes that could damage your liver or nervous system upon degradation (mainly getting heated up). Short term exposure is okay, but long term could cause major health issue. Copper can bend around stuff (good for complex pipping). But on the other hand Copper seems like it could be corroded (since metal) not sure if copper causes any major health issue.
It depends if your health conscious or if you want durable pipping.