I like Fang, but Chief is such a fun villager to have around. He acts all tough at first, but once you get to know him better he softens up and becomes a bit of a diva about his clothes and furniture. Definetely my favorite wolf and favorite cranky villager.
I was at first wanting Fang to match with Whitney later, but I saw that Chief set his plot up perfectly and also got an in-game look at him. I love his sly facial features and he is seriously such a sweetie to have in my town. I shall have to say Chief as well.
I've had both in my town, but I find Chief boring and inferior by comparison not to mention I loathe the inside of his house. I'd personally go with Fang.