Voysey bath panels should generally be Shaker style panels, to match other furniture in the bathroom. And either Oak or painted to match other finishes in the room. The number of panels is a matter of personal choice, whether it be 1, 2 or 3.
You could also wrap the bath in oak panels, including the cut-out bath shape. Voysey did this himself in at least 1 bathroom. This is very much a period look if you go for it. Most people would shy away from an oak top these days, for hygenic reasons & probably preferring the cleaner look of the bath. But it is 1 option.