I'm starting to think that stamina tanks vs. avoidance tanks is sort of like the different healer classes (i.e. Paladin healers vs. Druid healers).
In some cases Hot's are preferred. In some cases big spike heals are preferred.
Similarly, in some cases maximizing effective hp is preferred. In some cases maximizing avoidance is preferred. The good news is, healers can't change classes, but tanks can build up multiple gear sets and/or get new enchants and gems.
Or.. there's always the third option of balancing your stats in between stacking stamina or stacking avoidance.