Have all three out of the three i would say go for crysis good multi, good single but short and its sorta like 3dmark 07! (people use it to benchmark lots)
Cod4 fun on par with Crysis
Bioshock only sinlge player so you can just "Aquire" it
UT3 not my type of game, most weapons are the same as ut4 i found. But a fair amount of new vehicles and updated graphics personally i dont like pray and spray