I think people mean to say that this is the best fury spec:
http://db.vanillagaming.org/?talent#LV0bZE0zm0xRIt allows you to have enough rage to Intercept, Shield Bash or Hamstring after switching stances, while giving all the advantages of fury.
Most importantly, you get Piercing Howl and Improved Intercept, which means improved mobility and sticking power. While Arms does get 5% more crit as well as Impale and Improved Overpower, Fury still does more damage due to Enrage (25% damage bonus) and Death Wish.