The thing about
My Heart Is a Chainsaw is that there are two books that come after it.

Most of what I've seen from Jones is Horror, except for some of his very early stuff, which is barely readable. Lansdale is awesome, whatever genre he's writing in.
I will point out that I enjoyed the heck out of
I Was a Teenage Slasher, in spite of not liking slasher movies, and in spite of not liking most of the music the book's characters live for. On the other hand, I seem to enjoy reading Horror much more than you do, in general, so that probably explains most of the difference.