If I had a choice between PVC and PEX there would be no more thought about it. I would go PEX. It will just burst without throwing fragments. Easier to run and replace, and it isn't brittle to begin with.
I don't care for black pipe because the moisture will rust and the rust will clog up the couplers/tools if you don't have a trap at each end, and if I had to use a solid line I would go copper over black pipe.
