Can't name my favorite without at least mentioning my top 5
In order, #1-5: Dogs, Horses, Betta fish, Snow Leopards, and Capybaras
Dogs are my favorite animal for the following reasons:
1. Highly adaptable; both large scale throughout the thousands of years of domestication and small scale in how they adapt to a variety of living conditions
2. Incredibly empathetic; new studies in cognition and behavior show that dogs are capable of affective empathy. Dogs are able to not only smell(!!) emotions (they can pick up the different hormones in our sweat) they also have the ability to understand basic vocabulary (similar to that of a 2-3 year old toddler).
3. Species diversity: there are over 300 different recognized breeds worldwide. From the tiny, delicate Papillion to the majestic Borzoi; from the stocky furry Chow chow to the delicate hairless Peruvian Inca Orchid, there are so many wonderful dog breeds, each with their own unique and fascinating histories.
4. Near limitless potential: Seeing eye dogs, loyal best friend, guard dogs, police dogs, emotional support dog, psychiatric service dogs, cardiac/seizure alert dogs, therapy dogs, protection canine, exercise buddy, a part of the family, swimmer, hunter, tracker, retriever....dog can do so many different things!!!! And each dog is wonderfully unique, both from a 'nature' perspective and a 'nurture' perspective.
There are many many many more reasons, but i'll stick with these as my top 4!!