A choice *between champs*

So i have a tournament coming up , i have team : adc-lucian , supp-leona , jungler-amumu , mid-syndra .Now i need help , because i can`t decide witch is better Renekton or Gnar. Now i know , i should play what i am good at ,{{champion:92}} is my main , and i can`t play with her at the tournament because my opponents know what i main , so they are going to ban her . Now i need help deciding , Rene or Gnar ?
Report as:
Offensive Spam Harassment Incorrect Board