Don't get Ninja Gaiden Sigma. It is awful. Really, really awful. It hates the player. With a vengeance.
From what I've played of Resistance (not a lot), it is nothing like Halo, and is quite unique.
LBP go ahead
MGS4 has an excellent single player campaign, with a great story. The online isn't as horrible as people seem to think, it's actually very good. The only annoying thing is that you have to sign up for a GAME ID and KONAMI ID on the website- it's not done through PSN, but through Konami's servers. MGO is very different. You have the classic cardboard box, great shooting, and several game modes, one (two) of which DOES (do) involve stealth.
Uncharted has great single player, but the multiplayer is awful, mostly because there isn't any :P
Warhawk is a love it/hate it thing. There's a demo on PSN, try it.
(Former) Lead Moderator and (Eternal) VGC Detective 
