by DrearyYew » Sun Aug 30, 2015 10:27 pm
Druids: Versatile, but have by miles the weakest scaling in the game respective to other healers. This won't be a problem through leveling and into MC progression, but later progression they will really fall off and become good old innervate bots. Have no real res, but have a Battle Res on a 30m CD, making them undesirable for dungeons unless a Spriest or Ret Pally is already in group. Druids are also strong in PvP, but it's for their flag carrying, not healing.
Priests: Share the spotlight with Paladins as the main healers of Vanilla. Fear Ward if Dwarf is incredibly powerful. Unlike Paladins, Priests have very versatile healing options for almost any situation. Will lead healers on shorter raid encounters. Holy Priests, while they have some good utility, are generally the weakest PvP healers, due to mana issues as well as having very few survivability options with their cloth armor.
Paladins: The sustained healers of Vanilla. While they lack the healing option pool of a Priest, they greatly make up for it in their utility through buffs, Divine Shield, Blessing of Protection, and Judgements. Unlike Priests, Paladins have very little mana problems, and in Naxx gear, will pretty much never run out of mana. Paladins are easily the best PvP healers through their extreme tankiness and utility, near infinite mana pool with extremely efficient heals, and near immunity to CC through Blessing of Sacrifice.
I know you were looking more for Leveling, but you're going to end up doing dungeons and raids or pvp at max level, so it's worth knowing how things work at that level. Generally, Druid healers are undesirable while leveling, and the difference between Paladin and Priest while leveling is negligible. Priest is better when your tank has shit gear, and Paladin is more useful when the tank is well geared since their buffs increase the DPS of the group.
Dreary - Human "Needs No Mana" Holy Paladin