I like one that can be both a backpack and carried over the shoulder. The backpack option is great if you plan to babywear, you will look like a bit of a pack horse, but it is useful. I have the Mini Kapoochi classic and it does this, at times though it is a bit big, so I have a small shoulder bag for short trips. Even now I look at other nappy bags and wonder if a different bag would have been better. Overall though I am happy.