I'll dabble around in a lot of things, but I find mystery, horror, and the supernatural tend to be my go-tos. Even if those aren't the base plot, they always end up creeping in sooner or later. If it has monsters, I want it.

Superheroes is another one I'm more likely to get behind, simply because it's so easy to AU. If you don't like modern day, try putting some of those characters in another era and see what comes up.

I also like slice of life, but it [i]has[/i] to be with extraordinary characters/situations (fandom-specific, give me a handful of inmates at Arkham just getting on each other's nerves, forming alliances, and making enemies over who took the last pudding cup). I don't care about Susie worrying about who's going to take her to prom; I want the Riddler and the Music Meister being forced to share a cell, learning each other's tics, eventually planning an escape utilizing both of their talents, then becoming on-again-off-again partners in crime (did that once; it was tons of fun).