The original slasher Black Christmas (1974) holds up well; unsettling, bleak, and scary imo

Rec, it's a pov Spanish language horror from 2008 but set in a building that could easily be a setting for 70s-90s. Kinda like Blair witch in a haunted house. Some jumps but the suspense is built for the bigger scares.

Candyman (1992) it's not exactly unknown but I think it's recognition falls behind other 90s horror movie& series. Philip glass soundtrack, multiple conflicting myths & legends, scares that are suspenseful and gory and unexpected.

There are a couple alternate soundtracks to Nosferatu (1922) that make it more scary and less dated

Edit: for more thriller less bloody I'd go with Hitchcock & the movies he helped inspire like Brick, Blue Velvet, Dark Passage, Basic Instinct