If you are taking 1k damage or more then its something like a mountain buster. In this case WAR is a better tank because of Storms Path and Inner Beast which will reduce the MB by 30% where a PLD will only reduce it by 20%.
Also, WAR will get topped up much faster because not only did the MB hit for less, WAR have 20% increased healing. In the games current state i think PLD are better for AoE tanking and WAR for single target tanking.