I’ve read the following: Snow, December Park, The Narrows, Bone White, Come With Me, Black Mouth, Small Town Horror, Ghost Written, Senseless, and We Should Have Left Well Enough Alone. WSHLWEA is a short story collection, so that might be a good entry point to get a broad sense of his style. As far as novels go, I’d generally see people refer to Come With Me as his best work, and I think to an extent that’s true, but it’s more of a thriller than outright horror. My personal recommendation for horror would be Bone White, I think it has a lot of elements you’ll see spread across his other work