Well, I can say with certainty that Gormenghst didn't satisfy me as a fantasy novel. And I don't view any element of it as "distinctly other". Odd, yes. Disturbing, yes. "Other", no.
I have read The Lions of Al-Rassan. It was an ok book. Also did not satisfy me as fantasy. Tigana, on the other hand, did satisfy me as fantasy. There were distinctly "other" elements in it.
I am not familiar with KJ Parker or any of his books. So I don't know.
I quite like Tigana. I like all of Kay's work, though. Parker is best known for his Engineer trilogy, I suppose, or for the works he writes as Tom Holt. I like his books as well. The publisher's description of The Company is:
"Hoping for a better life, five war veterans colonize an abandoned island. They take with them everything they could possibly need - food, clothes, tools, weapons, even wives.
But an unanticipated discovery shatters their dream and replaces it with a very different one. The colonists feel sure that their friendship will keep them together. Only then do they begin to realize that they've brought with them rather more than they bargained for.
For one of them, it seems, has been hiding a terrible secret from the rest of the company. And when the truth begins to emerge, it soon becomes clear that the war is far from over. "
It's basically a story of looted war gold and the human nature that comes to the fore amongst this group. Nothing supernatural. It is Fantasy only in that it takes place in a made up world. Such a story could easily have played out in real history. I liked it, personally.