Heres my number 5 Worst horror movie:

1. Homecoming (Worst Zombie movie I HAVE EVER SEEN! Its about Zombies who come back from the dead for the right to VOTE!...AS ZOMBIE AMERICANS! NO JOKE! WTH!?) lol
Heres the trailer since most people might not believe me. http://www.youtube.com/watch?v=93jdPg5xNY0

2. Jack Frost (the mutent snowman)
3. The Girl Next Door (2007)
4. House of the Dead
5. Creepshow 3

My Top 5 favorite horror movies but not in order cuz they all are good:

Dead Birds
Rosemary's Baby (a 60's movie)
The Omen (the old one not new)
Hellraiser
American Werewolf in London

Theres alot more but this would be a REALLY long thread if I put every movie I liked and hated since I've been watching horror movies since I was 6 years old.

Id say my favourite 5 are in this Order

1) REC
2) Silent Hill
3) REC [2]
4) The Hills have eyes
5) Creep

Not sure about my least favourites.. I hated the first Resident evil though

Umm the only thing on my worst is The Stepfather, it sucked REALLY BAD!
my top 5 go:
1. The Exorcist (which still scares me when I think about it >.<)
2. Rosemary's Baby (The 60's Exorcist o,o)
3. Audition (Japanese film, in one of the first showings half of the audience fainted, vomited, or ran away screaming)
4. Texas Chainsaw Massacre (Best Slasher!)
5. Poltergeist (The clown scene)

The 5 Best
1.The Incredible Melting Man (Personal Favourite)
2.Friday the 13th Part 8
3.Halloween (1978 version)
4.Jaws
5.Amityville 3D

THE 5 WORST
1.Hell Asylum (Oh crap this movie sucked the only reason I own this film was because I bought a 10 movie pack for 50 cents and this was one of them)
2.Anaconda 3
3.666 The Beast
4.Haunting of Winchester House
5.Nightmare on Elm Street 4

Best:
The Shining
Storm of the Century
Pet Sematary
Joy Ride
and some more I forgot, I am very picky when it comes to horrors lol.

Worst:
All Nightmare On Elmstreets
All Jason Friday the 13ths
All Halloween movies past the 2nd
All Final Destination Movies
All Saw Movies Past The First

Basically I think 99% of horror movies blow they are just way too predictable and boring and cheesy.

I don't really remember any bad ones apart from like 2 but heres are the best and worse of what i can remember:

1>silence of the lambs
2>Halloween
3>saw
4>the hills have eyes
5>sixth sense (favorite movie ever but not the scariest)

5 worst
1>dead at the box office
2>all those American teen horrors like the one with the scarecrow

I actually did this in my profile.

FAVORITE
Halloween 1,2, 4
Friday the 13th
The Tenant
American Psycho
Shining

WORST
Everything Saw 1
Jeepers Creepers
Feast
Shining (The tv version)
The hills have eyes

My Top 5...

1. The Texas Chainsaw Massacre
2. The Collector
3. Silence of The Lamb - Though it wasn't at all scary but very good.
4. The Brood
5. Eraserhead

Worst 5..

1. The Omen
2. Rosemary's Baby
3. Carrie
4. All Nightmare on Elm Street
5. All Jason movies

The worst horror movies I have ever seen are:

Freakshow (it is actually banned in 48 countries)
Dead Alive (it was meant to be a kind of disgusting comedy, but it wasn't)
Hellraiser 2
I Know What You Did Last Summer
Valentine

Now the best I've seen are:

Last House on the Left (the original and the remake were both awesome)
Saw (the first one was the best)
Friday the 13th (only the first few)
Nightmare on Elm Street (ditto)
Halloween (ditto)

Let's see: 

The best:
1. Silence of the Lambs. - it scared me a little, but it made me jump more than anything, haha.
2. The Exorcist. - I had nightmares about this one. =|
3. Poltergeist. - Same ^
4. The Shining. - I was afraid to watch this in the dark. >.>
5. Jaws. - it made me a little afraid of the ocean. >.>

All of them excellent films, in my opinion. 

The worst:
1. Saw 2 and beyond. - just gore fests. /yawn
2. Hostel 2 - yeah, it scared me, but it was still a stupid movie. =|
3. I Know What You Did Last Summer. - eh. 
4. Freddy vs. Jason - never seen the whole thing, but what I did see just looked kinda stupid. 
5. Any Jaws beyond the first (because the first one is awesome). 

Oh well let's see if I can think of some horror movies I think are best/worst....

The Best (IMO):
1. 1408
2. Poltergeist (all 3 films)
3. A Nightmare On Elm Street (Original)
4. Halloween 1 & 2 (Original)
5. The Grudge (Trilogy)

The Worst (IMO):
I can't think of titles right now, but ANYTHING from Full Moon Pictures. They never get good actors and the story-lines always stink.

Ooo-ooo this is fun!  Hmmm, this is going to be hard, I can barely remember all of the horror movies I've seen so far but here goes:

The Good - 1. All of "The Thing" movies (including the recent remake)
                     2.  C.H.U.D (Bloody creepy)
                     3.  Dead Birds  (This one also scared the rainbows out of me>.>)
                     4. All of "The Grudge" movies (creepy moving chick crawling down the stairs??? come on, dude...thats not even funny)
                     5.  The Visitors A.KA Besokarna (never heard of it? look it up. Its sure to scare the skin off of ya.


Ok, This is NOT going to be hard:

The Bad - 1. Megashark Vs. Giant Octopus ( Dang, that was a dumb freakin movie...but then again, all of SYFY channels are stupid--
                   2. Jason X (Jason in space??? WhY? o.O
                   3.American Werewolf in Paris (bad....just bad.)
                   4. Darkwolf (the transformation scenes will make you cry of laughter and misery)
                   5.  Moby Dick 2010 (omg LOL!  This movie sucked so hard! Whatever you do...do not watch this movieXDDD