This past October's Monster Madness, AVGN did Top _ Horror Movies for different eras/time periods of horror movies, and put the cutoff at 1989 essentially, saying that there really hadn't been enough good horror movies or new cultural pushes in the genre to merit a top list.
I've been thinking about that and the more I think of movies, the less that sounds like earnest critique and more it sounds like he just didn't feel like it. There have been plenty of excellent horror films in the last 26 years; it's ridiculous to insinuate there haven't even been ten, so it's not worth digging to list them (not that I'd mind doing so at some point). But the era-split ... I know that gets tough because of inane remakes and shitty sequels, but it's ignoring a couple of trends in the genre, for better or worse.
One is found footage films. Yeah, they didn't originate then and most of them suck, but The Blair Witch Project's success did start something and good things have come out of it. A bigger push has been Asian horror. Not just the movies themselves, but the remakes/rip-offs that have been made in the west. Even good ones. And there's a lot to go through that never really crossed over to the west, but overall the unique supernatural horror from various eastern countries has had a cultural impact globally, not just in home countries.
This doesn't really matter; I just think it's ridiculous to shrug at the last 26 years and suggest there's been nothing of note or quality.