Many plumbers are switching to PEX systems.
It's a product that's been used in Europe for thirty years.
Copper is still widely used also. The link below has a copper sizing chart that helps with standard issues. It's a good idea to read up a bit on it ifyou're considering doing your own plumbing.
Water pipe sizing
If a system is sized right, you will not even be thinking about except in good glowing terms.
A poorly sized system will rack your brains.
Piping information here