priest's are the best class in the game ^_^ disc are the best if ur twinking. disc can alslo give of the best heals. holy on the other hand always has good heals but unlike disc when ur holy ur mana drains away quickly. shadow... well dps of course.

What do you find best for leveling? Mine is holy and while he heals like a witch on fire, he really does burn through his mana tooo fast!!

disc is definitely what u want if ur either twinking or lvling... people say shadow is best for lvling but shadow is no good when u have more then 1 mob on you and as disc u get spells that give u 15% intel when the talent is maxed out aswell as a talent that allows mana regen while casting

When lvling my own priest I did Shadow up to around lvl 64 then I switched to Disc. I would say go shadow until you get to Outlands then go Disc. There really aren't bad problems with multiple mobs until Outlands anyway and you can still heal instances as a Shadow priest in early game instances. Being Disc will help a lot in Outlands to keep yourself going while you fight several mobs. That is also when you get penance which is the best part of being Disc. And as Disc you can very easily heal most 5 man instances with a tank who can hold threat. Disc is best for 5 man groups and for tank healing but Holy is a much better raid healer.