Just got World of Worldcraft..........

[Bodhesatva]

Another note: be careful what class you choose! While there is always some flexibility in a class, there are some things that each class will simply never, ever be good at.

Priest: Heals/Damage. Those are the strengths of a priest, and you can't really do them both simultaneously. It's one or the other. When you first see a Shadow Priest -- who does damage -- you will think "Holy crap." Shadow Priests are one of the best solo class/specs in the game. I play a Paladin and a Mage, and regardless of which I'm playing, when I'm alone and I see a Shadow Priest, I turn and run.

Paladin: Heals/Survives. In some ways, that combination makes Paladins the best "healers" in the game -- because ulike Priests, Paladins are really hard to stop. I personally love it, because I can stand there in the middle of all the enemies and they can't do a damn thing to stop me from healing, but a LOT of people dislike it. When you're playing a character for a long time, it gets painful when you can't kill anything. And trust me, as a Paladin, killing won't be your strong suit. 

Shamans: Heals/Damage/Survives. The amazing thing is, a Shaman can do all three of these things at once; a Shaman can theoretically be a killer, a healer, and a survivor all in one build at one time. This sounds amazingly awesome, but it definitely has downsides; first of all, you aren't quite as good a healer/damage/survivor as a Priest or Paladin would be at their respective jobs, and second, Shamans are extremely susceptible to CC (crowd control, like turning someone into a sheep as a mage). That may not sound important now, but trust me, CC is an extremely crucial part of the game, and Shamans weakness to it matters later on. A LOT. 

Druids: Heals/Damage/Survives. Unlikely Shamans, Druids are only really capable of doing one of these things at a time; they can either be great healers, damage dealers, or survivors, but never three or even two of them at once. The upside is that you really are GREAT at your job when you choose it and stick to it; Druid healers are some of the best in the game, Survival druids are amazing PvE tanks, and Cat druids dish out as much damage as a Shadow Priest does. 

 

Hope that helps. There are obviously other classes, but these are the only healing one. Let me make this point clear, because it's important; any of the four listed classes could be the "main healer." You do NOT need a Priest, and there are not obviously the best healers. All four of these classes are effectively equally good at healing.