They both look about the same price to me
Seriously though, i've read quite a few place's the Dead Space 3 has quite a weapon custimization part to it, where you salvage parts and make your own weapons. And you cant actually get the best parts ingame, you have to buy them like DLC. Apparently this is quite sold to you as you play and you can feel like your sold short on that part of the game.
If you can overlook this though I've had plays on both and both are pretty fun! Crysis 3 has a more active online game though, that might be worth thinking about, and Dead Space 3 you can play the story game in CO-OP with a mate!