Your chances of survival in Antarctica from a crashed plane are incredibly low. Freezing temperatures, high winds, no water to consume without the risk of dropping your core temperature faster, and no source of food. Couple that with the risk of bad weather at the bases preventing a rescue attempt and you have a dead flight. At least in the ocean you have a chance to create a raft from floating debris, you can rig up a system to give you drinkable water, more easily reached by different types of would be rescuers, and the chance to catch fish. I'll take my chances in the Pacific.