I personally prefer plastic backed adult disposable diapers because I love the smoothness of them and I find they also hold in the wetness better as well.
With cloth backed adult diapers I find that sometimes the urine will seep through a bit through the cloth backing which causes wet spots on my pants.
Plastic Backed disposable diapers keep the moisture inside the diaper where it belongs and they just feel much better.
Also plastic backed diapers can be taped onto myself much tighter which keep the diaper from stretching and sagging and falling down which makes it uncomfortable.
With cloth backed diapers you can adjust the Velcro more but they tend to not hold up as good and plastic backed diapers can be taped tighter even though you cannot tape the plastic backed diaper over and over again.
For me I love wearing the plastic backed diapers but I will also sometimes wear cloth backed diapers.