I've got SH3 and SH4 for the PS2 and man, they're the best when it comes to survival horror.
And they're also awfully tough towards the end with the boss monsters, and although I haven't finished SH4 yet, but you really need to work real hard in SH3 to unlock the bonus stuff and the Heather Beam.
I highly recommend this game to the fans of the survival horror series. Looking forward to get my NAD for the PS2 so I can bash zombies together with my friends in RE:Outbreak and of course, waiting with bated breath for the grand daddy of them all - RE4.