The Hunter is the easy button for leveling. Your pet holds the mob, you shoot it from range, and you barely take a scratch. You can grind for hours, you almost never die, and you can solo elites that other classes need a group for. If you want to get to 60 with the least pain, this is the class.
The catch is that "easy to level" and "easy to play well" are two different things. The Classic Hunter has a melee dead zone, a window between point blank and ranged where your auto shot does not fire, and a shot rotation built around weaving Auto Shot, Multi-Shot, and Aimed Shot without clipping your own swings. The gap between a good Hunter and a bad one in a raid is enormous, and most of them are bad.
Hunters also bring the best utility ranged pull tools in the game. Feign Death resets threat and saves pulls, Misdirection does not exist yet so your Feign is how you dump aggro, and your pet brings a buff to the raid depending on what you tame. Tranquilizing Shot, Tranq Shot on enrages, and traps round out a kit that does far more than just shoot arrows.