Two things to consider with regard to mitts (well, at least IMO):
Softness: I CD-test, but remember to test with both the CD and the mitt wet with wash solution. Materials that'll scratch dry won't do it when they're soaked in shampoo.
Free-rinsing: some mitts (SM Arnold MF ones come to mind) really retain certain types of dirt and that can lead to marring.
I use all three types of mitts and they all have pros and cons.