I've had both track and wheel drive snow blowers and I'll take tracks. So much more traction and no more having to "help" the snow blower when the wheels slip. As for chains, hate the rough handling chains give to the machine.
All this time I have forgot to mention (not sure if the wheeled versions will do this or not... the few I have ran did not) You can tilt the tracks up or down so only the front or rear edges are making contact with the ground to help it dig into the snow/ice. You can tilt the machine back on the tracks as well to make it easier to move/transport.