> Why you love them, why you hate them, cliches you don't want to
> see, something you want to see more of?
No matter how sick your serial killer is or how gory the killings are, I think we've reached the end of that line a long time ago. Once you try and escalate that aspect of the story, you fall outside the M/T/S genre and into the Horror genre.
If anything, I'd like to see plot lines that side-step serial killing altogether. For example, serial killing as a means to cover-up a targeted murder. Or serial killing which is in fact someone attempting to erase his/her dubious past. Or serial killing as a means to achieve a laudable end (ex: Kurtz in Apocalypse Now - eliminating VC double agents). Those sorts of villains are not whack jobs, but rather have a specific goal in mind while still being worthy opponents to the Hero.
-cb