How is this even a question? 80s easy. The best franchises and sequels to the most schlocky and B budgets films to the best horror remake of all time with The Thing. Slasher films. Horror comedy. Serious horrors like Aliens. Using practical effects. Practical effects are like Pizza. Even bad they have their charm. When great nothing is better and again I point to The Thing. Tom Savini. Rick Baker. Stan Winston and more. The greatest minds to ever work with practical effects. It's the most iconic era as well. Horror had so much range then more than ever. You can like other decades more,that's fine but to choose anything but the 80s...you're wrong. The 70s may have given birth to the slasher flick but 80s gave it life. 70s had some good stuff but most of it was forgettable. 80s gave us everything from Aliens/The Thing to Friday the 13th to Freddy to Ghostbusters/Monster Squad to The Gate and Ghost Story plus so much more.
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.