Posting your opinion with no evidence is worthless. Crossposting the same into the simple questions thread means extra points.
I have seen the question of Best Alliance Mage Class asked more than a few times, so I shall answer this as follows...
Although the idea of "Best" could be up for debate, through my experience the Ideal allliance raiding class for a Mage is Worgen. The 1% increased Critical Strike chance has it's obvious advantages for a raiding mage.
Some would argue that a Draenei may be a bit better, but there is more than enough +Hit gear available to meet the requirements needed.