most of my favorite movies are Horror movies.
American Werewolf in London, John Carpenter's The Thing, Evil Dead II, The Exorcist, Alien, . . .
i even classify the original Terminator as Sci-Fi/Horror.
my ALL-TIME favorite Horror movies are the classic George Romero 'Living Dead' movies. (minus 'Diary' and 'Survival')
NIGHT of the LIVING DEAD (1968 )
DAWN of the DEAD (1978 )
DAY of the DEAD (1985)
NIGHT of the LIVING DEAD (1990)
LAND of the DEAD (2005)
RETURN of the LIVING DEAD is definitely among the favorites as well!