Favorite anything is subjective.
All relative to your current existence.
To attempt to select one film, song, band, producer, etc is futile.
Favorite is subject to change at any time.
I watch around 6 to 8 movies per day.
I'm disabled and homebound and I have a lot of movies.
There are some which are good anytime and there are some I shut off within 5 minutes.
Having seen so many movies it would be a very long list to try to list all that I really like.
Even if I were to try to list the movies that always capture and hold my attention would result in over 100 movies.
Trying to limit it to 5 films is very difficult.
Plus, those 5 films change according to my mood.
Here are 5 horror films I think are worthy of watching:
(In no particular order)
Altered (2006)
R | 1h 28min | Horror, Sci-Fi, Thriller | 20 July 2007 (Italy)
Forever damaged by their stint as the scientific subjects of hostile alien creatures, a trio of alien-abduction survivors -- Otis (Michael C. Williams), Duke (Brad William Henke) and Cody (Paul McCarthy-Boyington) -- troll the wooded site of their disappearance, heavily armed, in search of their attackers. After wounding a violent alien in the woods, the three drag its dying body to the home of reclusive fellow abductee Wyatt (Adam Kaufman), barricade themselves in and prepare for the worst.
Altered - Trailer
http://www.youtube.com/watch?v=vjDEeCVDlKE
Aliens (1986)
R | 2h 17min | Action, Adventure, Sci-Fi | 18 July 1986 (USA)
After floating in space for 57 years, Lt. Ripley's (Sigourney Weaver) shuttle is found by a deep space salvage team. Upon arriving at LV-426, the marines find only one survivor, a nine year old girl named Newt (Carrie Henn). But even these battle-hardened marines with all the latest weaponry are no match for the hundreds of aliens that have invaded the colony.
Aliens (1986) Trailer #1 | Movieclips Classic Trailers
http://www.youtube.com/watch?v=oSeQQlaCZgU
Deep Rising (1998)
R | 1h 46min | Action, Adventure, Horror | 30 January 1998 (USA)
A newly unveiled ocean liner, the Argonautica sets out on its first cruise, only to encounter dangers both on board and in the ocean depths. While the beautiful thief Trillian (Famke Janssen) attempts to steal riches from the boat's wealthy passengers, the ship encounters major problems, most notably a giant murderous sea creature with tentacles. Eventually, a boat captained by John Finnegan (Treat Williams) comes across the Argonautica, and everyone struggles to survive the monster.
Deep Rising - Trailer
http://www.youtube.com/watch?v=R6De_A9T07A
The Relic (1997)
R | 1h 50min | Horror, Mystery, Sci-Fi | 10 January 1997 (USA)
Thrilling tale about a deadly creature at large in the Chicago Field Museum. Following several grisly murders, a policeman teams up with a biologist to find the demonic force stalking the corridors of the museum. With the museum's gala opening being imminent, they face a race against time to track down the creature before it strikes again.
The Relic - Trailer
http://www.youtube.com/watch?v=Zm25s3T4SDM
537 The Relic All Sightings YouTube
http://www.youtube.com/watch?v=s4VCDAcyvrk
Godzilla: King of the Monsters (2019)
PG-13 | 2h 12min | Action, Adventure, Fantasy | 31 May 2019 (USA)
Members of the crypto-zoological agency Monarch face off against a battery of god-sized monsters, including the mighty Godzilla, who collides with Mothra, Rodan, and his ultimate nemesis, the three-headed King Ghidorah. When these ancient super-species-thought to be mere myths-rise again, they all vie for supremacy, leaving humanity's very existence hanging in the balance.
Godzilla: King of the Monsters Final Trailer (2019) | Movieclips Trailers
http://www.youtube.com/watch?v=6prr2MIHE0Q
Godzilla: King of the Monsters 2019 - Burning Godzilla
http://www.youtube.com/watch?v=_PkntN2bvw8
Granted what I call horror and what IMdb calls horror are two different things but frankly, I don't give a damn.
Here's 5 more movies I like:
(No particular order)
30 Days of Night
Death Factory - Bloodletting
Demons (Demoni)
Evil Dead
Hellraiser
And 5 more...
The Hills Have Eyes
Jeepers Creepers
Laid To Rest
Mirrors
Offspring
and 5 more...
Phantasm
Pumpkinhead
[REC]
Ripper
The Collector
and 5 more....
The Crow
The Messengers
The Prophecy
Unnamable
Wishmaster
see what I mean, I could go on and on with movies I really like.
I refuse to even try to name just one favorite above all others.