A mitt slips over your hand and covers more area, a pad gives you a slimmer profile for panels and contours. Both work, so pick by feel. Deep plush pile matters more than the format.
Deep, soft pile pulls grit up and away from the paint, holding it in the fibres instead of grinding it across the panel. A thin, cheap mitt keeps the grit against the surface.
Rinse it in the clean bucket between panels, drop it and it is done, and wash it after every use. A mitt that touched the ground will scratch, so bin it rather than risk the paint.