Dark Souls
Great combat, beautiful world, hair tearingly difficult combat (until you learn how to fight well, then it becomes less difficult and more about being careful and not getting a big head). Story is pretty interesting, but its not really given to you, gonna have to read up and pay attention.
Soul Calibur 5
Got it on launch and do not regret the purchase. They took away a good bit of options from some characters from IV (ex. Mitsurugi lost a stance), but what they added more than makes up for it once you practice a bit, get used to the new and improved gameplay (except the lack of free guard impact...), and don't go into it expecting a magnificent story (its a two hour long story mode. Most of the old cast isn't featured and if focuses around the whiniest character I've seen in awhile).
As for a third...haven't played them besides a demo for Bulletstorm. Didn't care much for the gameplay in the demo so I wouldn't recommend it. Heard Arkham City is good though. Plus you're Batman in it. BATMAN. Need I say more?
EDIT: Hm..somehow I managed to miss Deus Ex on that list. Deus is a great game, found it very fun, but you might only get a couple of playthroughs out of it. While that is still well over 40 hours of gameplay if you don't rush, the playthroughs past the first get kind of tedious when you listen to EVERYTHING everyone wants to say.