CoD: no personal experience, hear mediocre to good reviews, multiple people have said it plays like a WWII total conversion of CoD4 Fable II: also no personal experience. Been hearing mostly good about the game. Fallout 3: I'm running PC version, it's awesome but it's hard (you know how generous Oblivion was with potions? Expect 10x less stim packs.) I hear the 360 version is the superior console experience. GH: also no personal experience, and no feedback.
Sorry I can't give solid comparisons, but I will recommend Fallout 3 if you liked Oblivion or STALKER or similar games.