I know what you're thinking. You're thinking, "This is a chicken-or-egg scenario! How can I choose when both are vital to survival? I love both! Don't make me pick!" Now you're lying on the floor, cradling your head and whimpering.
Seriously, stop being a Charlie Brown and take a side! Are tanks more important due to their scarcity and skill that it takes to juggle aggro and take all the pain meant for others? Are healers the mostly unsung heroes of raids, forced to stare at shrinking green bars instead of getting to eyeball the action?
Let's put this bickering to rest, daddy wants to take a nap. Have it out after the jump: tanks vs. healers. I expect that this will put an end to centuries of violence surrounding the subject.