Arcanine, the more physical attacker of the two. Ironically has lower base speed than Ninetales, despite being known for its legendary speed.
Arcanines Bulbapedia page
Ninetales, unfortunately has a lower base stat total than its counterpart. This does not lower its usefulness on the battlefield, however.
Ninetales bulbapedia page
So which do you think would win? Personally my vote is with Arcanine. On design, and usefulness.