good question..
here's what I would want..not in order of importance: automatic turner, forced air, automatic humidity control, digital temperature control, removable shelves and turners for ease of cleaning, individual compartments so that you could open and check one compartment and not disturb the rest of them.. accurate temp and humidity readings... good visibility to the inside without opening any doors..
for cleaning : the abillity to hose it down(inside and outside) with a high pressure washer without damaging anything..