Yes, anime/manga is popular, but I've seen others of different persuasion- comics, movies, and in particular to the BBC not only Doctor Who but also Merlin. In fact, every other year, I have cosplayed at Supanova, I have always been a movie or a literary character. This is my first year I'm doing an anime one.
So go for it- I think Sherlock's pretty popular but what's just as good is with the popularity of anime/manga, your costume will be noticeable and has a smaller chance of being worn by others- so unlike mine, lol.
Briznova 13- Clara 'Oswin' Oswald, Eleventh Dr's Tardis, Dalek Drone (New Paradigm variant)