I'd have to say the Grunny. Because not only is it a cute item all by itself, but it's a big part of Gaian history and reminds me of all that was going on with the outbreaks and the G-corp when I first joined. It represents the fun events that Gaia always comes up with to suck us into something more than just gold farming. smile
Coco Kitty hands down. I was so happy when Gaia came out with another kitty plush of a different color and with unique poses/positions (I always used to equip it on my avatar's face and back). Though it was a bit of a bummer that we can't hold it with the avatar's arms down, I really like that pose with the Kiki Kitty.
Well, I loved it so much that I ended up buying two for 9k each when they were released. * V *
♥My personal favorite would be golden fleece, because you can both look like an absolutely adorable golden lamb & be fashionable with a cute gold scarf. It's not something I'd actually wear, though. The dreamer's dust, however, I definitely would equip; it's blue, has a mystical feeling to it, and goes well with a lot of outfits.