Paladin
Pros: Nice big heal, Hand of Protection/Hand of Freedom, nice buffs, Aura's, Lay on Hands (15 minutes with Glyph
), Purify (Removes Posions), Divine Protection (great for staying alive while healing others), and Hand of Reckoning (for keeping people in combat and inturupting healing). Also, if mana becomes an issue judge wisdom and take a few swings at the opposition for good mana return.
Cons: Not mobile, only one interupt (and it is on a 1 min CD), purify only removes poisons (well and diseases which aren't present in PvP), Holy Light has a slightly long cast time, and isn't the best for mana efficency. Also, healing on the move isn't viable, and only Aliance Paladins have a HoT (With a 2 min CD).
Druid
Pros: Great HoT both for HPS and MPH, Regrowth is a nice sized heal that leaves a HoT, and Healing touch is a good big heal all of with leads to great healing versatility. Has nice universal buffs, can cure posions, and a useful debuff in faerie fire. Can maintain a utility role while healing with roots, hibernate, and faerie fire. Wrath and moonfire can be used to helf finish off a character, and moonfire in particular can me spamed to kill a runner/push back healers. All this plus we haven't mentioned bear form...Survivability high, melee interupt, roots, twin debuffs (AP and Armor), good for mana regen, and a good way to lead DPS away from your other healers.
Cons: Healing is gimped when a shaman/priest is present and removing HoTs/Buffs/Debuffs/Roots. Not as good for healing in Arena's OR Premades...more a pug healing class. When forced into bear shapshifting can be mana intensive. Survivability in caster form is a bit low.
Priest
Pros: Dispell (Huge advantage at 19), has both a HoT and a big heal thus healing versatility, has a bubble (Preimtive mitagation OR quick life saver), Psychic Scream only on 30 second CD and targets 2 characters (lots of versatility), wand DPS is viable and cost no mana good for regen and DPS, universal buff and solid self buff, Shadow Word: Pain is a good DoT and has great utility (Keeping people in combat, keeping people from stealthing, keeping people from bandaging), and lastly Mindblast/Smite for finishing off people.
Cons: Squishly (more so if bubble and psychic scream on CD), HoTs aren't as good as druid, has to be in range for psychic scream or no inturrupt (which is bad for a squishy class), and can't remove poisons (with lots of hunters can prove to be anoying).
Shaman
Pros: Most mana efficent big heal, Purge (OP like preist dispell at 19), also remove posions, and tremor totem for fears and sheeps (best debuff remover at 19?). Shocks only have a 6 second CD this screams utility, and with totems even more. Soild DPS while healing weither ranged or melee. Great self buffs with weapon boffs, and lightning shield, and high servivability from totem use with leather and sheild.
Cons: No HoT, Long cast time on only heal, no mobility when healing, no mana regen ability and some what gimped DPS when out side of 5 second rule (so weakers DPS when waiting on mana regen, and major lose of utility). Weakest party buffs (if you even want to call totems party buffs
).
Rankings (In my opinion)
Healing:(Multiple Targets)
1. Druid/Priest
3. Paladin/Shaman
Healing:(Single Target)
1. Priest (HoT, Bubble, and Big Heal)
2. Druid (HoT, Mid Heal w/HoT, and Big Heal)
3. Paladin (Big Heal, Bubble, and Lay on Hands)
4. Shaman (Big Heal, ???, and ???)
Healing:(While Moving)
1. Druid/Priest (HoTs)
3. Paladin/Shaman(NoTs...JK)
Healing:(While being attacked, interupted, or CCed/Slowed)
1. Druid (Shapshifting > CC, Instant cast Hot > interupt, Roots + Bear form > DPS/push back)
2. Priest (Squishier, and less HoTs(kind of))
3. Paladin (One heal long cast time, more armor, and shield...so will be there healing for longer then shaman)
4. Shaman (One Heal long cast time)
Survivability:
1. Paladin
2. Druid
3. Shaman
4. Preist
Utility:
1. Shaman (Purge, cure posion, totems, and shocks)
2. Druid/Priest
4. Paladin (Utility CDs are too long)
DPS:
1. Shaman (Melee, Totems, Shocks, Ranged cast, weapon enhancements, and lightning sheild)
2. Priest (Wand + Shadow Word: Pain)
3. Druid/Paladin
Arena Viability:
Sorry results vary for 2v2, 3v3, and 5v5! But I would say all are viable for Arena play if specced/glyphed/geared for Arena. That is some are more so for 2v2/3v3 and others more so for 5v5. Here I will try...
2v2/3v3
1. Priest/Shaman
3. Paladin (Gets owned by interups)
4. Druid (but not by much)(gets owned by purge/dispell/interupts)
5v5
1. Shaman (Utility, Survivability, Healing, and DPS)
2. Paladin/ Priest
4. Druid (still not by much)
Premade Viability:(as a healer)
1. Priest (I would take two)
2. Paladin/Shaman (One each on D?)
4. Druid