I went through the same thoughts you've been going through. I've asked around at numerous Gamestops with employees and this seems to be the consensus.
-Vanquish is a highly recommended rent. Great adrenaline fused gameplay but a short campaign with a shitty story.
-Enslaved has a great story, but the campaign is too short and the gameplay is pretty good but not great.
-Castlevania has great gameplay and good story and is over 20 hours give or take of gameplay.
I bought Castlevania and right now I do not regret my purchase. Plus, I just got Gamefly so after I finish castelvania its Vanquish, then enslaved.
The force unleashed was the game I actually pre-ordered, but the game only has six hours of gameplay. I watched a guy at my dorms play it. It was amazing yet saddening to see how short it was
