So then the better way to evaluate it would be to do so on a few levels:
  • Tankbusters Only - Assume incoming regular damage at ~200% max HP once a minute, and all other damage inconsequential. This is roughly the way the current tanking meta works, so evaluating each of the tanks' ability to soak this damage (or, to achieve at least 50% total mitigation). This would look at stacking buffs and their interplay to see who can do it best. This damage should be assumed to be magical most (if not all) of the time.
  • Consistent High Physical Damage - Since the majority of this game's content consists of medium to high amounts of incoming physical damage, evaluating the tanks' ability to mitigate this damage should also be a focus. For this one, buff stacking would generally be kept to a minimum, and the calculation would need to account for Parry, Block, and self-healing. Incoming damage could be said to be 20% HP/sec. This would basically mimic big trash pulls.
  • Mixed Physical/Magic Damage - This evaluation would be similar to the previous, only it would include saving big cooldowns for regular magic damage. So assume 10% HP incoming damage per second, with a once-a-minute magic nuke of 75% HP. This would probably be close to what you'd see in a dungeon context on some of the harder bosses (looking at Stone Vigil for inspiration here).

The amounts I've picked are all ballpark estimates, but would provide a good baseline for evaluating a tank's ability to mitigate incoming damage across a variety of contexts. You could theoretically also do calculations encounter-to-encounter, to evaluate mathematically which tank is best for each, but that would be crazy amounts of maths.