I prefer night. In the far south of wisconsin the light isn't that great druing the day (overcast flat light a majority of the time). And the snow is always icy so I prefer the better lighting with the lights.
night skiing is fun because there are less crowds but every time I've gone the park is iced over with divots in the landings. the best though is night skiing when there is a bit of new snow and skiing unilt runs with a headlamp. super fun.