copper vs pvc compressor lines?

Black iron pipe over copper definitely. PVC No Way! In some areas copper pipe is not allowed for compressed air due to codes. The copper pipe joints are sweated together & therfore the pressure rating cannot be guaranteed. Yes copper pipe is rated at a few hundred psi, but the solder joints are the weakest link. Black pipe isn't that hard to work with & can be cut & rethreaded to make any length you need. It's also cheaper than copper too.
Good luck with your project.