Honestly as much as I enjoy the 80s is probably the most overrated decade for horror in my opinion. Theres some good stuff from that decade but it rarely goes far above being good. The best from the decade is probably the shining and the thing, but horror just got very dumb and formulaic in the 80s.

To me this is an easy question to be honest, its the 70s. Its got what I consider the single 2 best horror films in history in Jaws and Alien, which not only are fantastic as horror films - but also fantastic as films, overall, in general - I'd argue they are amongst the best films of the decade.

Add to that its got some cult classic that I absolutely love, like Wicker Man, Phantasm, Eraserhead and Suspiria and absolute classics that have trascended the medium like The Exorcist, Halloween, Texas Chainsaw Massace, Carrie, Dawn of the Dead, Invasion of the Body Snatchers and many more. 

Not to say there arent that many standouts in every decade, the 80's got Aliens and The Thing, which are amongst my favorites of all time as well, and this current decade has been particularly good to the genre, but the 70's hit my sweet spot.

Missing Chucky stabbing a kids menu

This has been an insane decade for horror/thrillers:

(nice balance of some slasher, paranormal, and more basic thriller/suspense with some experimental stuff. 2000s seem to lean a bit too heavily on the paranormal & zombies while 90s was cheesy slashers which don't always do it for me). And alot of 80s stuff and beyond tends to feel dated for me unless it's a major classic like Exorcist, Night of the Living Dead, etc..

The Lighthouse
Creep
The Boy
Babadook
The Witch
Sinister
The Conjuring
Insidious
Krampus
Little Evil 
Hereditary
Calibre
The Invitation
Get Out
The Quiet Place
Us
Train to Busan
The Awakening
Cabin in the Woods
New "It" (pretty fun though I'd also say overrated)
New Child's Play was ok but somewhat interesting new take on the series, and better than I thought. 

Also hear The Wailing is awesome though still haven't seen it.

An awful decade for straight-up comedies (though oddly a handful of great thriller/comedies like Krampus) which is a shame as it's probably my favorite genre but horror's are a close second so that makes up for it I'd say. 

For me, the 1980's.

The 1980's, without a question. The Evil Dead (1981) has inspired so many other horror movie directors, The Fly (1986) is breathtaking in every point of view, Hellraiser (1987) is one of the most iconic horror movies ever made.

The handmade special effects in the 1980's horror movies are overwhelming, more scary and more believable than today's CGI - and there are no boring mobile phones.

I also like some black and white movies from the late 1950's / early 1960's from Hitchcock. Some weeks ago I saw Tarantula (1955) for the first time – and it was really impressive (because it was filmed with a real spider). CGI is really overused in today's horror movies. I don't like it. And I don't have the impression that today's directors have the freedom to make such movies like Eraserhead (David Lynch, 1977) or Braindead (Peter Jackson, 1992).

No Halloween 2018 or It?  Probably my favorite two of the 2010's.  On your list I would say Sinister is my favorite, that movie was excellent!

The '80s has An American Werewolf in London, so that's enough for me to vote for it.

I agree with you 100%. The 70s is the best for horror films. Plus, it gave us Deliverance, not a horror film exactly - but mighty scary indeed.

Just watched upgrade yesterday, it had an interesting blend of sci-fi, action and body horror, well worth a watch.