I really liked The Skeleton Key, I think it deserves a special nod. The plot is really well thought out and interesting to follow, it's not just a bunch of a people getting murdered in succession. That has it's place though! I also think Cabin in the Woods is one of my favorite horror movies in recent history. I really like it because I've been a fan of this board game Betrayal at the House on the Hill for many years, and there are some elements the two things share. Be sure to pause the movie when you get to the part with the whiteboard. I personally wasn't a fan of insidious and I didn't see the sequels (so they might be a little better than the first). I was super disappointed in The Babadook after getting hyped up for it. I just wish the ending had been more to my liking, and I wish it wasn't the morality tale it turned out to be.
Kinda artsy if you're not into that but I enjoyed Antichrist. Looking through my Netflix history, you guys might like Deathgasm, it's Heavy Metal being played backwards/Dungeons & Dragons/Demons themed, it's pretty silly though with over the top gore. Not a terribly serious horror movie if that's what you're after. Oh! "Satan's Little Helper" is pretty amusing. I highly recommend that one, it's kind of a dark comedy and it's pretty ridiculous. It's about a little boy who thinks Satan is really awesome from a video game he likes, then he finds this masked serial killer who he thinks is Satan and unwittingly helps him do terrible things. Jug Face was sort of interesting, it's been some time since I've seen it but I remember liking it. Sorta redneck/backwater kinda horror stuff. Melancholia was personally terrifying to me, it's not a traditional horror movie, but it's got a scary concept. The New Daughter was pretty good, as was Open Grave. I watch so many horror movies I can't keep them all straight.
As for older ones:
Ravenous is pretty weird and disturbing, it's about cannibals during frontier times (maybe civil war era? Been a while.). Great soundtrack on that one. Frailty is one of my favorite religion themed movies, it's about a man who is spoken to by the archangel Micheal and told to slay demons who are posing as people. He gets his two young children involved in his work.
Classics: Invasion of the Body Snatchers (Important! Donald Sutherland 1978 version! It's the best and scariest one), The Shining (original only!), Dawn of the Dead (Both old and new are pretty good, actually), Return of the Living Dead (but none of those retarded sequels!!!)
I also just remembered that I watched "Holidays" on Netflix, it's a bunch of horror shorts based on holidays. Some are better than others, but it's fun. Easter was probably my favorite one, I think. Kevin Smith and his daughter are both featured in that, as director/actress respectively. Speaking of, I haven't watched Tusk but I am going to try to this weekend. I also want to see if I can find "The Visit" and check that out too.
One last weird suggestion: Black Mirror on netflix. It's more of a sci-fi anthology series about technology, but the show is so dark, it could fit the bill for some halloween watching. Season 3 just came out and it's all so good! Watch it!
I tend to prefer older movies but these were all really good as far as more recent horror movies go:
Slither
The Conjuring (all)
Insidious (all)
A Haunting in Connecticut
The Possession (sadly the US only got the PG-13 version, there is an unrated version out in Germany though...)
Dead Silence
Wrong Turn (mainly 1 & 2, but I enjoy them all)
The Skeleton Key
A l'interieur
The House of the Devil
The WNUF Halloween Special
Kill List
[Rec] 1 & 2
I really don't get all the love for The Babadouche, I was so bored with it and also found the ending to be very predictable.
Looking forward to checking out the new Carnival of Souls and City of the Dead (Horror Hotel) BDs on Halloween but will probably watch at least 4 or 5 other movies as well! :]