Which game is better in your opinion?

BioShock, as it's the only one of those I've played.

Better game - Dead Space 
Better story - Bioshock

I like Bioshock better but Dead Space is awesome.

Bioshock for SURE

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Bioshock.

I don't think they really compare being put side to side in all honesty. Dead Space was far superior and just more fun gameplay wise though.

They are both awesome games, but I love Dead Space soooo much more.

Love them both and I don't really think they're the best games to compare side by side, though I can see the parallels you can make between them -- stroy-driven; claustrophobic feeling in a strange environment; killing strange, deformed creatures with weapons you can upgrade; etc.
 
Overall though, I'd have to say Dead Space. The story left me wanting to learn more about the before and after of the Dead Space universe, the gameplay was phenomenal, and the game was so much fun start to finish. Bioshock was a great game, had a fantastic story and setting, but the combat felt somewhat monotonous and unpolished. 
 
By the time Bioshock was over, I felt I had played all the Bioshock I needed to play -- the story had a definitely beginning and end, enough closure was provided, and I had experienced enough of the gameplay to be thoroughly satisfied. Dead Space, on the other hand, was a very satisfying experience, but left me wanting even me more.

Bioshock. Love it's atmosphere.

Dead Space, definitely. I loved the feel of the game much more than Bioshock, although I do still love Bioshock.

I thought Bioshock was a lot more interesting, but I also didn't completely hate the combat in Dead Space. I'd have to go with Dead Space.

I liked them both, but I prefer Dead Space by far.  I couldn't put that game down.

Bioshock, no contest.

I won't pick any of them, as I haven't played Dead Space and Bioshock didn't capture me at all.

Dead Space, no contest.

Dead Space is my choice. Bioshock just seems really overrated to me. I have played it for a number of hours and am yet to get sucked into the world or story. I just don't get it.