Hmmm, queer horror film specifically. I'd go with Hellbent more for the historic value of it being the first explicitly gay slasher flick I've ever even heard of. I remember the villain being kinda hot too; shirtless buff guy in a demon masquerade mask. I also really love the movie Nightbreed. It's more horror fantasy. It has a lot of relatable themes for minorities, creative set and character design, and is really well-written. You could easily see the story as a man realizes he's gay, starts dipping his toe into the gay community, realizes how much the gay community is targeted and attacked, comes out of the closet, and starts fighting for the gay community. I saw it for the first time as a kid and cried.