What are the key stats (most important stats) for every Class?
I heard that for a Warlock the stats Spirit and Intelligent  are the most important ones. Is this trough?
And what are the key stats for the other classes?
(I just want to know, because I play with all other classes :)  ).

Thanks.

Ehm... Depends on what do you want from the class(tanking rogue with >75% Dodge? Why not? Hehe). Well:
Rogue/Hunter=Agility(+Crit/+AP/+Dodge/+Armor)
Warrior=Strength(+2AP/Block Rating)
Casters: Mage/Warlock/Priest/Sham/Pala/Druid=Intel(+Mana Cap/+Crit)
Healing Priests/Shamans/Palas [or Mages(usually they've enough mana, so nvm)] could also prefer the Spirit stat for some reasons of the "Allows x% of you mana regeneration to continue while casting" items/talents. Lock will never need Spirit. Forget it, you've been lied to.
Melee Pala/Druid/Sham... well... Strength.

Ok. Thanks.