I would choose Coral Reef---Marakesh was not a good experience for us.
Plus the fish tank is always there to enjoy--the bellydancers are on and off again.
I've never been to Marrakesh, but We really really loved the Coral Reef. The atmosphere, and food was amazing. Our waiter was kinda wierd but by no means gave us any bad service.
I will be trying the Coral Reef in three weeks and can't wait.
Marrakesh wasn't good at all for us. Out of all the years we have been to WDW it was the bottom of our list! The wait staff were rude and unfriendly. The food was bland and no flavor, we will not go back.