Both the Fuel and the GTO are built nice and strong, giving you better chances of your kite surviving a wave crash. The GTO is lower AR, easier and faster to relaunch(thus again minimizing chances of wave damage on a downed kite) and the way it turns is pretty sweet for making quick direction changes, it offers really smooth power and seems to handle gusty winds more friendlier than the Fuel. Those are the traits that make it stand out in the waves.
The fuel turns really fast too though. So fast that I am finding that alot of riders are tuning them to slow them down a bit. The fuel can be tuned to fit your wave riding needs as well.
I ride mostly Fuels. However, I ride mostly on flat water. IF I were riding waves most of the time, I'd prolly be flying GTO's more than Fuels.