Sad to say, but I really haven't played a "Survival Horror" game in a long while. Resident Evil 4 is more of an Action Horror (if we count it it'll be my favorite. Superb game.) and Silent Hill: Shattered Memories is definitely a Psychological Thriller (and a great game as well, I may add). I've only watched a friend play Eternal Darkness, and the Light Gun games featuring zombies ("Mutants!" -Agent G) are just... light gun games.

So if we're going by the purest sense of Survival Horror, I guess it'd be REMake. If we're being a bit more lenient, then Resident Evil 4, followed by Shattered Memories. I dunno... Survival Horror is really becoming such a niche genre due to its tight constraints.

well the scariest ive played is siren blood curse.

the section where you play the little girl in the hospital and cannot be seen by gouls otherwise you die, was down right nerveracking

Resident Evil 2 followed by Silent Hill 2 and Condemned.

System Shock 2

"Look at you Hacker. A Pa-pa-pathetic creature of meat and bone. Panting and sweating as you wander my corridors. How can you contend with a perfect, immortal machine?" - Shodan

Seriously, that sent chills down my spine just from writing it.

Resident Evil 3. How many people Shit themselfs whenever the Nemisis would show up and the bonus Mercenaries game after finishing the story was brilliant aswel.

My favorite is silent hill 1 with Resident evil 2 and 4 comes close (very close). I still remember the chills and shivers when playing the game. The Static from the radio when there's an enemy nearby, the scenery is just freaking scary and the famous fog from silent hill but if you are going to ask the scariest, for me it's fatal frame 2.

Silent Hill 2. For me the gold standard for this sort of thing.

gears of war

Eternal Darkness.

Resident Evil series in general.