I will say that I don't purely focus on a specific type within a genre.  I might have some purists, but I tend to spice things up a little, as well.  For instance, in a fantasy, I would not have just caster-types, but other classes, and there would be some bleed-over because people don't always focus on one thing themselves.  Much as Gandalf is a wizard, he is accomplished with a weapon, as well.  A supernatural creature would further have its [i]own[/i] way to handle things, and people in fantasies who are not mage-types may find magic items.  And I've done as much modern fantasy as classic, too.

Still, that's neither here nor there.  I'm going to assume we're not vying for the extremely devastating in foes here, but rather something that ranges from formidable to shocking.  Is that about right?  I'm just trying to decide what angle (good, bad, guy with the gun, blue-and-orange morality, amoral, etc.) to work at with this.  As a possible suggestion or two on the sci-fi end, it could be pure cyberunkery (with normal cyborgs, robotics, hacking, etc.), space (with ships, aliens, and whatnot), or hell even Shadowrun.  I love Shadowrun.

I wouldn't mind horror, although it's ultimately more likely that I would play something horrific and a person who generally combats such things, as I have alot of inspiration in that area.