Definitely Battlefield 3.
Fallout 3 is a very good game, but it looks horribly outdated and will be bad with the rift I think.
Either you need a really good ‘photorealistic’ game like Battlefield 3, Crysis, Portal, Project cars, or a game with a particular style like Minecraft, Borderlands, dishonored.
Old games which tried to be ‘photorealistic’ looks very bad today. For exemple I can easily play at ratchet and clank because the cartoon style doesn’t look outdated, but games like the first tomb raiders, Vice city etc just look bad