I think polar bears are cooler. They're big and scary, and big scary animals have always had a tough time staying around for very long because they need so much territory to survive in. Pandas are cute and all, but I don't want to run out of scary animals on this planet. If I could bring back some species of massive carnivorous dinosaur, I would even though we'd be basically sacrificing that land for them.
Are we talking about a fight? A Polar Bear would tear a Panda apart. So Polar Bear.
Are we talking about an adorability contest? Well, the Panda would be lookin all super cute and adorable and the Polar Bear would come up from behind and shank that silly bitch then settle in for a meal. So Polar Bear.
If it's a math contest though, Panda Bear. You know what they say about asian bears and math.
The one that has to hunt other animals to feed itself while being about 4 times larger, has shown very high levels of intelligence and still exists under improbable conditions.
The one that sits around eating bamboo and can't figure out how to survive in a controlled environment with the best possible conditions and mating partner.
Put all pandas in the murder slingshot.