Both versions of Riku have a horrendous taste in clothing, but I'll go for older Riku for the sake of the poll. He did look awesome wearing the black cloak.
Xigbar was the Nobody I liked most (after Xemnas, I'm more evil oriented), it was kind of sad to see him go away. Even though he didn't quite look like he was dying, just teleporting somewhere else. Demyx was most dramatic, and Xemnas' false death (where Sora asks him if he really doesn't remember how it was to have a heart.) was also quite saddening. Especially him saying "Unfortunately... I don't."