What's up Tarv? You bored or sumfin?
I'm surprised by the number of people trying to post "serious" answers.
As soon as a Cleric gets past 19 they have a superiority in healing that cannot be surpassed at any level.
The very essence of the Cleric class is healing with a myriad of nuances.
I played a Druid to 61 as a primary healer and before playing a cleric would have argued that they are very effective healers, in particulay since the addition of Healing Waters to the game.
Now having played a Cleric to 52 and already gathering up the 53 and 54 spells in anticipation, I can say that there is little comparison.
When pushed into being main healer as a Druid I now feel distinctly handicapped and highly stressed knowing what the shortfalls are liekly to be under "x" or "y" situation.
If you want to be analytical about it, it boils down to two key aspects to the task of healing, mana efficiency and time.
A Druid can compensate for the lack of refinement in most situations by simply having a vast supply of mana. But there are some situations where time is even more important than the mana regen/useage equation.
When you get the situation where you have multiple people dying with adds in camp, believe me it is a Cleric you want, not a Druid or Shaman.
A competent Cleric with his/her combination of fast heals, heals over time, group heals, death recovery and reverse damage shields can get enough healing flowing to his/her group to keep them alive in situations where a Druid or Shaman would have simply been forced to watch people drop all around them.
Yes Druids/Shaman I know and love Chloroblast, but when the chips are really down it just can't cut it by itself.
But that is only half the story.
And yes it is with great humility that I acknowlege Leiany, Cobra, Cortte and others with regard to the DB tactics I'm about to mention
If the superior mana eficiency and time management capability of the Cleric was not enough, the point that tips the scale on its head is that a Cleric can manage all of this with a fraction of the aggro risk.
All healers know that if there are loose adds in camp pretty much any sort of heal will bring them on to you.
The Cleric's range of stuns, root, Atone and yes Divine Aura/Barrier etc give them the tools to manage this in a way that the poor old Druid can only dream of.
For most of my time as a Cleric healer I have relied on stuns and root, with occasional use of Atone to keep the unruly adds in check until assistance arives. The basic issue being to keep interupt free so that heals can be cast on those in need. However after reading the posts about DA in Leiany's recent thread I decided to spend some time working with it this weekend. I reluctantly (at first) gave up the nuke slot and memmed Divine Barrier.
I was grouped with some pretty good people for most of the weekend, but eventually the situation arose where I would have struggled through with stunning and roots while taking something of a beating, and I got the chance to use it.
We had a Necro doing CC and caught a stray wanderer just after the puller had pulled a few (I think we had all got a bit casual as things had been going so easily). So I had the cleric's typical nightmare. MA and second MA both tanking, the Necro taking bad hits while trying to mez and the Wizzy being beat on at the same time, as soon as I cast the first HoT I could see a couple coming for me, I stunned, backed away dropped a couple of fast heals where they were needed and then hit DB and sat down to med. By this time the Necro had had enough time to get his mezz's landed the HoT had kept him alive, the one stray left had gone back to one of the tanks and joined the melee. I have to say that watching the mobs leave me and wander off to join the melee was a joyful experience. So after playing with this a couple of times I happily admit to being a convert to the DB tactic.
Any hoo, the point to all of this is that if your question was in fact serious Tarv, the Poor old Druid and Shaman are not even in the same paddock as the Cleric when it comes to the range of healing tactics they have available. A well versed cleric will alow a group to push further and take on far greater risk than a Druid or Shaman could ever dream of.