Different advantages of different roles

Generally there are four types of roles for almost all RPG, including Aion game. The roles are warrior, mage, knight, priest, respectively. As a whole, every role has its own advantage. Which one is the best, or better than other? The answer to the question depends on different people. If one likes one among them, the one is good. Currently, most people like the warrior a lot. The reason behind it is the warrior represents power, strength, and many more. The priest relatively is very rare. Many players suggest creating more races besides the four, such as soldier, commander and so on.