dead space or bioshock or valkyrie chronicles for ps3?

[ROBOTECHHEAVEN]

i played the valkyria demo and liked it, and i played the bioshock demo and like it, i have played all 3 of these games demo and like them all. i've been going back and forth for over 2 weeks, as to which game i should buy. valkyria and dead space i think are the 2 games i will decide between now.