When you choose a water line material, be sure that it meets the design purpose for potable water. Not all "poly" pipe is for potable water. Then be sure that all connectors and fittings are designed for the same pipe material and are for potable water. PEX has thicker walls, and either material should be bedded with a material such as fines to reduce the migration of rock from ground freeze/thaw conditions into the water line. (Perhaps that part was obvious.)
The interior diameter of PEX is slightly less than PVC. I think it was something like 0.93" instead of 1". By using a single roll, you will avoid pressure loss to elbows, but you may lose a little flow rate. I wanted 1.5" but the installer only had 1.25" or 1". As Twowaxhack noted, the 1" is the commonly used size for homes. I needed a high flow rate for a specific and out of the ordinary application, so the pump and lines were planned to deliver over 10 gpm in the house. The 1.25" PEX was difficult to navigate around turns, especially to get it into the house, and that required two people. 1" would certainly be easier.