Sword plushie, Chocobo hat and Moogle headband make the most sense as they relate to the forums we have. Personally, in an ideal world, I'd go for a chocobo or moogle plushie as it would be something that I'd cherish more. I wouldn't wear a headband so that's pointless for me. A sword plushie doesn't make much sense to me personally, although I can imagine some people might like it. But moogle/chocobo/moomba plushies would be incredibly awesome.

Also, what do you mean by chocobo hat? I mean, at first I thought of a giant half-chocobo head so that the beat sticks out front and you have two giant eyes or something. But then I considered it might just be a baseball cap with a chocobo on it. Which would rock, because I could never really wear the former option outside (I don't cosplay ). >_>;