I tend to write more male characters than female characters as well, but...I think why I do that is largely part of who I think my intended audience is. In RL & original fiction, when I write female characters, most people automatically assume that I'm being autobiographical, so male characters are more freeing in that sense to be sure...

In fanfiction? I think a large part of it is that the most interesting characters imo are men....and a great part of that is that the most interesting women always end up attached to someone by the end of canon, and her story gets wrapped up pretty neatly most of the time. What I love about fanfiction is being able to fill in the blanks, and I think that the characters with the most loose ends tend to be male--and that makes them easier to write and more fun to explore.