If any airport can handle winter, it's O'Hare and it's new set of parallel runways. With four potential arrival runways, the airport can close one at a time to clear the snow and continue using the remaining runways with no restrictions. Before O'Hare got the two new parallel runways, they had only two arrival runways in bad visibility conditions and that would drop down to one runway when the other one had to be plowed.

Even with only two arrival runways open, the airport can still land around 70 arrivals per hour without restricting departing aircraft at all. If the forecast is flurries or little accumulation, the airport won't even have to breathe hard to accommodate normal traffic. If it's going to be -20 degrees, then there might be ramp issues but no airport delay problems.

The nice things about O'Hare being in de-icing conditions, the airport is exempt from any FAA-originated delay program for any other airport. If ATC has given all LGA traffic an hour delay, the ORD departures to LGA will not be effected as they don't want recently de-iced planes sitting in line on taxiways gathering snow/ice on the wings.

Midway would be worse for delays with snow accumulation as it only has two usable runways at the airport for larger planes. Midway's runways are also quite a bit shorter than O'Hare's and when you have snow and ice on the ground, the longer the runway, the better. google "southwest 1248"