Midsommar. I watched it for the second time recently and it was even creepier, more disturbing and unsettling than the first time I saw it. So much sun drenched horror. Also, The Ring. It scared the living crap out of me. I watched it during the DVD era of Netflix. I remember running out to my car and sticking the DVD in the glovebox because I didn’t want it in my house. I also can’t believe The Blair Witch Project didn’t make your list! Simon! This was a brilliant, terrifying film shot on a shoestring budget that was mostly improvised. The actors - 3 unknowns at the time spent the duration of the filming out in the woods. Each day, they would receive a general outline of the storyline from which they would improvise. Think of all the found footage, derivative, mostly shiite films it inspired, including Paranormal and all its spin-offs.
Different category (sci-fi) but if you haven’t seen Aniara, I can’t recommend it enough. It’s one that will stick with you (I watched it a year or two ago and I still haven’t been able to shake it off). It’s a Swedish film based on a poem of the same name written by a Swedish poet in the 1950s. To call it prescient would be an understatement.