MGS4
Demon's Souls
Infamous
Including your list, I think those are the only exclusives worth playing. And I say this with a PS3 being the only console I own.
The exclusives that I once owned then sold/traded: Resistance 1 and 2 are terrible, ugly games with outdated mechanics. Killzone 2 is a screen tearathon with awful shooting and the weapons just "feel" wrong. White Knight Chronicles is an uninspired mess. Motorstorm is alright if you like brainless arcade racing but it somehow feels stripped down and bare. Valkyria Chronicles actually seems to be a fairly deep strategy RPG but I can't stand anime and the pre-teen main characters grated on my nerves.
I'm not really into JRPGs, and while I prefer to play FPS on the computer, if a console exclusive is good I'll play it on the console.
I completely forgot about MGS4, I should've put that one on my "Not Interested" list, same as the splinter cell games, I don't really like stealth-based games.
I mainly prefer story-driven games, which is why I don't play multiplayer. I'm also skipping multi-platform games because I have an Xbox 360 and I honestly prefer it. I mainly got the PS3 to play GT5, but I figured while I have it I might as well get some of the other games that are generally accepted as "Top Tier" games.
Demon's Souls is a pretty niche game. I'd rent it or try a demo (if there is one, I haven't looked) before buying it.
If you're a baseball fan, MLB The Show is a must-have. By far the best baseball sim franchise right now. The '11 version is out in early March, so I'd just wait for that.
Then you should take Enslaved off your list.
Anyways, given what you've added I'll third the recommendation for Valkyria Chronicles. Story centric, but without the typical JRPG gameplay (it's more of a SRPG).
If you like horror movies (and especially if you liked the ALIEN series) then pick up Dead Space. If you have a really good 5.1 surround sound system - crank it up and play Dead Space with the lights turned off for an experience you will not forget.
Dead Space was awesome.... on my PC 😛
Dead Space was awesome.... on my PC 😛