GT Pan. Not only does she whine a lot more than Supreme Kai, but more importantly, Supreme Kai had a GOOD reason to whine. After all, I'd probably cry out of fear, too, if some crazy, rogue wizard wanted to basically jeopardize the universe just for kicks and giggles.
Plus, he tried to stop the end of the world, and he admitted his faults, too.
GT Pan, on the other hand, was just annoying. Sure, she did stuff, but ultimately, her whining and complaining about normal stuff drives the point home that she's spoiled.