The great irony, of course, is that Lovecraft was an immense fan of Poe, and considered his own work vastly inferior to that grandmaster.
Me, I recognize that Poe is the greater, more literary writer. His work formed the foundation upon which most of the subsequent American (and to an extent European) horror built. Poe will always be the great enshrined classic.
But Lovecraft I find immensely more enjoyable. His purple prose, absurd situations, and yet immensely clever and unique ideas springing forth like the fevered dream of an ancient thesaurus seems to be the overwrought heart and soul of pulp. And still, he was enormously influential... where Poe worked himself to death in miserable lonely obscurity, Lovecraft's absurd volume of correspondence encouraged, personally, an entire generation of writers to start planting those fecund fields prepared by him and his idols.
But, of course, that wasn't the question. For pure creep factor, I have to go with Lovecraft, though not for the reasons most would likely proffer. Rather than the grand vistas of "cosmic terror" that most will cite as his best contributions, I've always felt that HPL was better in the clausterphobic, personal moments. It may be some error in my own reading, but HPL caught me off guard more frequently than Poe, and usually with something small... not the great forms among the mountains (Mountains of Madness) or the Godzilla-sized monsters he's known for, but the errant wet drop (The Picture in the House), the frantic cat (The Rats in the Walls), the smooth barrier (The Outsider), the slipped visage (The Festival) or the discarded mask (The Whisper in the Darkness).
(Kudos to Scatter on the miscegenation note... I'd begun to think I was the only person to note the likely and uncomfortable genesis of "Shadow over Innsmouth.")
