Savage Worlds and the Cinematic Unisystem have a major thing in common: They both have a metagame currency that can scale the whole thing up into the high level of heroic...but if you take that away, the game gets deceptively brutal and frightening. A Buffy campaign with all White Hats and scaled back drama points can get out of control, fast. Savage Worlds with a stifled bennie flow can do the same. The best part is, I know both systems well enough to get the "feel" for how to push and pull them to get what I want.
tremulus was alllllmost there, but honestly, I'm only a so-so Cthulhu guy. If it were veered for more "standard" horror than Lovecraftian, we might be having a different conversation. Fantastic game, though. Ghostories 2nd Edition, by Precis Intermedia Games, is another one that I want to toss out there from *reading*, but I've never actually *played* it, so it would be disingenuous of me to call it my "favorite".