The GMT gives you the option of swaping the bezel insert fairly easily and cheaply (IRO £30) so you could buy sepparate Coke and black insert so you get three different looks from one watch.
Explorer gives you the option of a white dial which only this and the Daytona offer in the sports range. Disadvatage is if the bezel gets damaged then you have to replace the whole bezel rather than just the insert.
Personally I would chose the Explorer