Purchasing an already established account allows characters to be transferred to different realms. There are a few restrictions but a clear and great benefit is being able to change your name once you have been moved to the new server. It is possible to move the character to another account which can keep the previous owner from ever being able to use it again and keeps them from stealing your money.

Another excellent selling point with getting pre-owned WOW accounts is that the gear is higher quality than simply power leveling your character. Your character can advance but you will still have the same low quality gear you had as an entry level player. Many websites selling these accounts come with guarantees and even insurance. It can seem to be the clear way to go if you are serious about moving your character up in the WOW.