My favorite has nothing to do with Anime actually.
I really love doing Scorpius as Harvey (From Farscape {Henson} which is very much live action anime) in the Hawaiian shirt cocktail in hand.
the hardest part of that costume was the facial appliance. I did a wonderful sculpt and made both hot foam latex and slip latex appliances, but didn't plan on the addition of teeth (prosthetic dental veneers) and the appliances are a rough fit around the mouth.
Currently once I get my shop fully restored from sandy, I am working on full body details / costume. and a new face cast / sculpt for the character
http://www.bbc.co.uk/cult/farscape/gallery/images/340/401harvey1.jpg