I see a lot of people saying Fable 2 is longer.  I've beat both games and I have to disagree.  Sticking only to Fable's main quest, it can be completed in about 6 hours.  I spent 10 hours on Dead Space.  I understand there are a lot of side quests in Fable 2 and most people will complete at least a few of them.  I would say I put in at least 20 hours, maybe more, into Fable before beating it.  However, Dead Space has some elements that give it replay value.  First, you can start another playthrough where all your weapons and upgrades carry over.  Also there are 3 default difficulty settings plus a 4th one that opens up after beating the game once.  That could easily bring Dead Space's play time equal to or more than Fable 2.

^ And Fable 2 doesn't have replay value >.>

my vote goes to Fable 2

Still, if you're one of those people like me that don't have that much time (or patience) to play a long game, Dead Space is good.
It's like 12 hours long plus the harder difficulties, you shouldn't buy it at full price though.

Get Fable 2. Its better gameplay and everything. Dead space isnt even close.

Dead Space. Done.

If your strapped for cash id say get Fable 2 as it will probably last you a lot longer than Dead Space.

I havent played much of my copy of fable2
but dead space would have to my game of the year
so i would go with that but its completely up to u

Even though fable 2 has more "replay value" i played through dead space 3 times and enjoyed it thoroughly while i played through fable 2 only one. They are both good games it really depends on what you are looking for ie/ fantasy/adventure vs third person survival horror

Dead Space is really good from EA I had my doubts about it at first but changed my mind after playing a few levels. haven't played Fable 2 since I am not a huge fan of RPG games.