Which is colder: The North or South Pole?

South Pole, thanks to the Antarctic Circumpolar Current. It acts as a shield between Antarctica and the warmer Atlantic, Pacific, and Indian oceans.

South because it is land-based

PO2 Russell "Russ" Lincoln
..."Arctic vs. Antarctic
The main reason the South Pole is colder than the North Pole lies in the key difference between them. "The North Pole is an ocean and the South Pole is a continent," Robin Bell, a polar scientist at Columbia University's Lamont-Doherty Earth Observatory in New York, told Live Science.

The Arctic is an ocean surrounded by land. The Antarctic is land surrounded by ocean. Water cools and warms more slowly than land, resulting in fewer extremes of temperature. Even when the Arctic Ocean is covered with ice, the relatively warm temperature of its waters has a moderating effect on the climate there, helping the Arctic stay warmer than the Antarctic.

In addition, whereas the Arctic lies at sea level, Antarctica is the highest continent, with an average elevation of about 7,500 feet (2,300 meters). The higher one goes, the colder it gets."...