I’m in the camp that leans towards it being Hellraiser. I feel like marketing is going to copy their strategy from last year, due to its success, aside from including a Blumhouse property due to the low ratings for two consecutive years. Have the marquee house (Stranger Things), the beloved classic property that appeals to general audiences (last year Poltergeist, this year Ghostbusters), and the classic horror property that appeals to general horror fans (Halloween 4 or Michael Meyers, Hellraiser or Pinhead.)
To flip that argument towards Freaks, you could argue that House of 1000 Corpses is the property that appeals to general horror fans and use Captain Spaulding for that.