So you would not believe how hard this is...so many fandoms to choose from.
I think I'm going to have to say Rose Weasley. This is mostly fan fiction Rose. I love Harry Potter and I'm so glad that J.K. Rowling left the door open. I have no doubt in my mind that Rose will be an interesting mix of her parents. Fan fiction is probably nothing like how J.K. Rowling would write about the next generation, but it is fun to read (and write...). Rose Weasley is one of my favorite characters in Harry Potter fan fiction.