Among the most interesting decisions to make in World of Warcraft are those concerning gear. Should a warrior prefer +Stamina or +Dodge%? Is +heal better or mana/5? Of course there can be no "right" answers to such questions. It's always a matter of "it depends...", but sometimes reasonable upper and lower limits can be found (e.g. 5 mana/5 will for all casters always be better than 10 spi). Another helpful insight is the Item level article, just to see which relative values Blizzard gives to different stats.