Not only is Golurk a lot cooler looking, but it also can fly.
Not good enough? Fine!
Golurks are so fun to use, their ability iron fist just makes a Golurk super strong, as they learn many moves that are enhanced by this ability. The fact that they are so heavy and slow makes them great for using trick room or Heavy Slam. Golurk has an innovative/awesome typing, that is very useful throughout Unova. Plus, it's offensive AND defensive, making it great.
Confagrigus, while a great pokemon, isn't as good ingame, it's typing isn't as fun and Ghetsis had one and it was terrible to battle. stall pokemon are so annoying
SO GOLURK ALL THE WAY!