I like the Halloween films up through Halloween V (1989). The rest is pretty bad except for H20 (1998) which is where the series should have ended. The Rob Zombie movies are not scary at all.
I like the Friday the 13th movies up through Jason Takes Manhattan (1989). The rest is garbage. The remake sucked.
My overall favorite horror film if I have to pick one is The Texas Chainsaw Massacre (1974). The first sequel (1986) is also pretty good but way different in tone. Parts 3 and 4 are fucking awful and should never have been made. The 2003 remake is good. The 2006 prequel is so-so. The 2013 sequel sucks but Alexandra D'addario stars in it... ( o )( o )
I like the original Romero zombie trilogy (Night, Dawn, and Day of the Dead) and their associated remakes (1990 version of NOTLD and 2004 version of Dawn).
Romero's new trilogy (Land, Diary and Survival of the Dead) are pretty bad...
I like Evil Dead I and II. Army of Darkness is trash. The Evil Dead (2013) remake is good.
I like Insidious and Sinister (the first ones). Insidious 2 is pretty bad and haven't seen Sinister 2 or Insidious 3.
I like Alexandre Aja's remake of The Hills Have Eyes (2006). It is one of the most brutal movies I have ever seen.
The most brutal and intense movie I have ever seen would have to be Martyrs (2008). This movie gives zero fucks about any of your sensibilities.