PVC, copper, tubing?
For ease of installation, CPVC is hard to beat. Flowguard Gold is a common brand that a lot of people around here use. Cut to length, clean, and glue.
PEX, which is flexible polyethylene tubing is an excellent product. It can be a DIY product, but you'll need to spend $100-150 on basic tools to do it. The pipe is cheap and you can bend it so you don't have to use nearly as many fittings. I'm a big fan of PEX systems, but don't like the basic crimp fittings that fit into a 1/2" PEX line and therefore neck it down to 3/8" due to the inner diameter of the fittings. I prefer the system with the expensive tool that expands the ends of the pipe for a larger fitting to avoid necking down at the fitting. PEX is also a great product in the event that your pipes freeze, because it will expand without bursting.
Copper is the old standby. I do most of my work in copper. But, it is crazy expensive these days. I spent over $14 each for 10' sticks of 1/2" last night, and most fittings are at least $1. It is definately a project for a competent DIY-er with a minimal investment in tools (torch, solder, flux, cutter, pipe cleaner). Copper will eventually corrode, but typically it will take a very long time for that to happen.
If I were re-plumbing my own house, I'd do everything concealed in PEX, probably with some copper mixed in at the plumbing stubs.