I have always assumed that cold would be better for an intelligent being to work in mainly because of electronics. Electronics work better in the cold than the heat. Heat also makes it harder to work. I have found it isn't that easy, though.
Hot can be considered better because most unlimited resources involve heat. The Earth's core, the sun, and movement in general produces more energy.
So considering all facts about hot and cold, which one would aid an intelligent species like humans the best? The most important thing, I assume, is how easy it makes it for the species to make tools and get the resources to change their own environment to suit their exact needs.