Does anyone actually prefer plastic bags? Even before there started being a push to ban them in some places, I was always kind of annoyed by them since they tear so easily if you put more than one or two items in them. I remember walking up the stairs to my last apartment with like twenty of them in my arms since I didn't want to make the trip any more times than I needed to and thinking to myself how much easier it would be if it were all in four paper bags or whatever.
For a large shopping trip, I hate plastic sacks. This is mainly because I hate ending up with 850 bags in my car, none of which will actually stand up and stay put while I'm driving home. But if I'm only buying a few small items, then I think a big paper sack is a huge waste (especially considering, as I said, the environmental toll of producing them), so I'll go for plastic instead.
When it comes to reusing them, each has its place. Plastic is useful when you need something leakproof: lining a wastebasket, dumping moldy food into, etc. Paper is useful when transporting things: bottles of soda and/or snack foods to a party, for example.