Just as Ricador said I would read reviews from each game from different sources. It all really depends on what kind of game you enjoy more, i.e. fps, rpg, strategy, fighting. For me, personally, I would get either Fallout 3 because that game has beautiful graphics and supposed great gameplay; or I would get Soulcalibur 4 because I have been in love with the Soulcalibur series ever since it began. Watch gameplay of the games on your list and trailers and ask around. That's all I would be able to say to help. Hope you make the right decision.
Out of your list Fallout 3 is the godly choice. I mean it's got some mad replay value like the other Fallout games. And the fact that it's like a first person shooting without taking turns makes it a whole lot more fun
Red alert is better for the ps3 and grid is one of the best racing games oout there but i would go with fallout 3 not mercinaires the reveiews said it wasnt that good.