What kills tank is not individual tank's EHP, but its the damage unpredictability and damage output exceeding healer's 'healput'. Warriors and pallys are designed differently, such that pallys are pre-damage management while warriors are post damage management.

To deal with burst damage, pally uses cooldowns, while warrior uses post damage heals. Against damage output, pally passively decreases enemies' attack, while warrior increases healer's 'healput'.

Overall, my conclusion is that pally is better when the group is less coordinated. Warrior will out shine pally when the group can leverage the improved 'healput' and damage boost that warrior provides.