fear 2 FAAAAAARRRRRR exceeds the fun factor in comparison to dead space. dead space is good for 1 play through, but thats about it (unless your forced to play it through because you have nothing else to play). dont get me wrong, i had a lot of fun with dead space, but couldnt bring myself to play through it more than once, even out of boredom. you basically perform errands the whole session, and its fairly predictable. On the other hand fear 2 is a proven series that got a really nice improvement with "fear 2". the solo campaign is alot of fun, the control mechanics are excellent, the atmosphere is involving and dynamic, and the online play is a lot of fun as well (never tried its online with ps3, only on the xbox 360). dollar for dollar, take it from a gamer who's been gaming for 30 + years, fear 2 would be the better choice, unless you are easily amused.
For Survival Horror- Siren: Blood Curse
For General Horror- Demon's Souls (although its technically an rpg) then Dead Space...other than that theres always Silent Hill Homecoming and Condemned two, which get a tie for best Horror game to rent. Oh and lest I forget Resident Evil 5, which blow the last two games listed away, although I don't think of it as a horror game at all, which actually makes it a lot better. IMHO you are better off withPS1 and PS2 games when it comes to both really scary-disturbing games(SH1-4, Fatal Frame, Kuon) and the more gorey-silly-campy variety (RE 0,1,2,3,etc. RE4)...the PC had some good horror-adventure titles for a while too although theres way too many to list.