The class you’re best at playing is the fastest leveling class. WoW is balanced pretty well. However, some classes do have innate leveling advantages. Druids- Great at pulling in loads of mobs at once. No cast time of Flight Form which is great for mobility at later levels. Mages- Great for crowd control and DPS. The more you kill the more XP you get. Demon Hunters- Best mobility of any class,  good AOE damage, and tough to take down. Hunters- Using pets allows you to pull in lots of mobs at once. You can handle group quest enemies on your lonesome with your animal friends