ABS vs PVC is often a regional thing..some places offer both, but it is more common to have one or the other. Use whatever you have the best choices in fittings and availability. Shower drains need to be at least 2" by today's code so you need to check what you have. IF it is 1.5", and you can't run new pipe to where it's at least 2", your inspector may allow you to just replace it with 1.5". While some showers may need a 3" drain, those typically have lots of heads and much more flow than a typical shower.