Snow on the ground takes on many different characteristics.
Nobody minds the light fluffy stuff, even in the the wet heavy slush your tires can get through to the ground for traction, and with studded tires and some care the hard packed icey glazed surface is not to difficult to manage.
So, what is the worst snow for cycling?
Right now we have the toughest snow to stay upright on when riding. It results from the compaction of about 3 1/2" of snow down to about an inch. The temperature is cold enough that the snow won't pack, it just remains a heavy granular mass on the ground that fills your tires' tread and squishes around as you ride.
Best short description I can muster is slippery 3/4" deep sand with a crusty upper surface with a hard smooth surface below.