I was tempted to vote for Zaraki at first, but then I started thinking about it. What does being the most GAR mean? Hard to say exactly, but more than anything it means that he has to be the most manly and impressing character in the group.
Zaraki is definitely the strongest, but come on, that's not all there is to it. Zaraki is a one-dimensional character who only cares about fighting and that's really all he has going for him. Claire on the other hand is just as badass in a different way; he's confident, has no qualms eliminating people he sees as the bad guys and is perfectly capable of doing so, finds a girl he likes and claims her as his own immediately, and gets away from the whole train incident completely unscathed despite what was going on.
James Bond may not be the perfect GAR candidate, but he wouldn't be a bad one. It's more than just how successful or strong the character is, that's just the bare minimum, it's about their attitude while they do it.
I'll vote for Claire for at least the next two matches myself.