Warlocks and Hunters are great for leveling your first character. Their benefits in the end-game, however, are not as useful as others. Warriors are always needed and so are Priests, and Rogues are good if you like PvP. A Druid mixes in all three, so you can cut corners there.

Previous MMORPG also helps with choosing a class. But I agree, Hunters and Warlocks are good for first-timers.