im levling drk , from 30-50 i went with whatever it dropped , after 50 im using a mix ,full str for low lvl dungeons tho... for HW dungeons VIT and change to STR if im not dropping below 50% ever (so far healers have been good enough)

in the end varies if the dungeon is easy and the healer is good STR all the way

if the healer is meh ,and u are almost dying every other pull vit