I quite like alot of modern Japanese Horror movies such as The Ring, Audition, The Grudge and Shutter, and to be honest the western remakes aren't terrible either.
For the lovers of zombie films, you should hold your head in shame if you haven't feasted your eyes on the amazing spanish horror film Rec, and avoid the shitty american remake Quarantine.
Anyway, I also like the original Halloween 1-7, The Thing, Alien, Dawn of the Dead.
In terms of modern, I actually enjoyed both Texas Chainsaw movies, and thought them superior to the original.
The only problem I have is I am rarely scarred my modern films, and to be honest thats sad, as I'm very easy to scare.
I think the reason is modern horror is all about blood (and not in a cool over the top Evil Dead sort of way), that's why I have recently enjoyed things like, The Strangers, Insidious and Them, as they deal with home invasion scenario's and all resulted in me talking to the T.V saying things like "Don;t go in there!" "Oh your f*cked now, you idiot", etc etc lol.
Also the FIRST Paranormal activity scared the shit out of me, the rest are rubbish. and of course don't knock The Blair Witch Project, sure its been parodied and laughed at for years, but it still spawned a genre and is actually quite a solid movie.