I've gotta say Akatosh, the master of time and father to all dragons. Dragons are my favorite mythological creatures, and Skyrim definitely had a lot of interesting ones (though I'm sure given their anatomy, they would otherwise be classified as wyverns instead...eh), and since Akatosh is depicted to be one as well, and because he's responsible for the existence of Durnahviir, Odahviing, Alduin, and Paarthunax, how could I not choose this Dragon Deity?